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Hawkins' 



Indicator 






Catechism. 



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THIS WORK IS DEDICATED TO 

HENRY RAABE, M. E., 

as a token of appreciation of valuable assistance in 

its making up, and a reminder of a long summer 

spent agreeably together in compiling and 

editing the author's new catechism 

of the Steam Engine. 



X ■ -f 



HAWKINS' 

Indicator Catechism. 



A PRACTICAL TREATISE 

FOE THE USE OF EEEOTING AND OPERATING ENGINEERS, 

SUPERINTENDENTS, STUDENTS OF STEAM 

ENGINEERING, ETC. 




RELATING TO THE DESCRIPTION OF THE INSTRUMENT AND 

DIRECTIONS FOR ITS APPLICATION IN OBTAINING 

THE BEST RESULTS IN THE ECONOMICAL 

PRODUCTION AND USE OF STEAM. 

BY 

N. HAWKINS, M. E., 

Author of "Aids to Engineers' Examinations, " "Calcula- 
tions for Engineers," the " New Catechism of the 
Steam Engine," etc., etc. 



THEO. AUDEL & CO., PUBLISHERS, 
63 Fiifth Avenue, Cor. 13TH Street, New York. 

T898. 



jL 



^ 



17133 



COPYRIGHTED BY 
THEO. AUDEL & CO., NEW YORK. 



■\ 



Gr* 




T" 



TWO COPIES RECEIVES* 

2nd COPY, 

I8gn 




CONTENTS. 



Introduction, ------- 15 

Preparing Indicator for use, - • • 23 

Reducing Motions, ------ 27 

Piping up Indicator, - » » - - - 37 

Taking Indicator Cards, 43 

The Diagram, - -■"".-- - ■ = 5 2 

Figuring Steam Consumption by the Diagram, 74 

Revolution Counters, ----- 76 

Examples of Diagrams, - 7$ 
Indicating Air Compressors, ---.•-■-- 87 

Description of Indicators, ----- 89 

Measuring Diagrams by Ordinates, - - - - 106 

Planimeter, ---••- 122 

Tables, - - • - - • • J 43 






/ 



/ 



■iiiiPl 



* l Much care is necessary in indicator practice, both of 
the instrument and its method of attachment, since so very much 
depends on a very sfnall area; and the engineer who obeys this 
rule, and puts a little thought into his work, will find there is 
nothing difficult nor mysterious in the use of the Steam Engine 
Indicator." 

— Thomas Hawley. 



i 



N 



T" 



■? 



THE STEAM ENGINE INDICATOR. 



The measuring instrument best designed to show the 
power of the steam engine is that invented by Watt — the 
steam engine indicator. 




Figs. 5 and 6. The Indicator. 




Fig. 7. The Indicator Spring. 



Note. — The purpose of the instrument is the same as a recording 
steam gauge, with this difference, that it records the pressure at each 
instant of the engine stroke, and this pressure is usually a variable one 
in different parts of the stroke. This is its object, simply to put upon 
paper the steam pressure pushing the piston at each point in the stroke, 
and at the same time to put on paper what pressure is opposing the 
piston at each portion of the piston stroke. That is all it does. The 
instrument may be considered as a steam gauge with a spiral spring to 
measure the pressure, and a pencil to record it. 



TO 



Hazokins Indicator Catechism. 



INTRODUCTION. 

The indicator is a miniature of the larger cylinder whose 
performance it is designed to reveal. The object of the 
instrument is simply to record the pressures that are in the 
cylinder of the engine at certain points of the stroke, and 
from this can be told, first, the action of the valve gear, and 
second, the distribution of pressure. This is all that the 
indicator shows ; it indicates how much pressure is in the 
cylinder, and the exact location of the piston when that 
pressure existed in the cylinder. 

Figs. 5 and 6 show an exterior and interior view of the 
American Thompson Indicator and Fig. 7 exhibits the 
spring which is the real measuring factor of the indicator; 
this spring is enclosed in a cylinder which is constructed 
so that its area is generally one-half of a square inch. 




Fig. 8. Indicator Spring. 



Fig- 3 19 is the piston rod of the Robertson- 
Thompson Indicator, shown in Figs. 10 and ir. 

These two instruments are shown out of a 
variety of excellent and reliable devices on the 
market, to which the following general descrip- 
tion will apply. 

The indicator consists of a cylinder of ^ a 
square inch area and about two inches long to 
Fig. 9. the upper end of which is attached an arm or 
bracket which carries a drum around which the 
indicator " card " is wound ; this drum has a diameter of 
about two inches and is capable of a semi-rotary motion 
which is given to it by a cord operated from the engine 
crosshead. 



Hawkins Indicator Catechism. 



il 



INTRODUCTION. 




Fig. 10. Indicator. 




Fig. ii. Indicator. 



The " diagram H is 
marked upon the card 
by a pencil which is 
on the end of a lever 
and which is attached 
by means of links to 
the piston rod of the 
indicator. Upon the 
piston is mounted a 
spring which counter- 
acts the steam press- 
ure ; these springs 
are of different ten- 
sions, or strength, to 
be used according to 
the steam pressure. 

To impart a straight 
vertical motion upon 
the paper card wound 
around the drum, a 
parallel motion de- 
vice, Fig. 12, is 
attached to the lever 
which carries the 
pencil. The one 
shown in the illustra- 
tion is the " Thomp- 
son parallel motion " 
and is that most fre- 
quently in use. 

This brief descrip- 
tion* of this important 
instrument will be 
readily understood 
by study of the sev- 
eral illustrations. 



12 



Hawkins Indicator Catechism. 



INTRODUCTION. 

The operation of the indica- 
tor is as follows : steam enters 
the cylinder of the instrument 
forcing the piston upwards 
against the pressure of the 
spring, this gives a vertical mo- 
tion to the pencil on the paper 
mounted upon the drum. The 
drum receives its revolving mo- 
tion by a cord which is wound 
around the lower part of the 
drum, its other end being con- 
nected by means of a reducing 
motion to the cross-head of the 
engine, which upon commencing 
its stroke exerts a pull upon the 
cord, thus giving the drum a 
revolving motion. This causes 
the pencil to make a horizontal 
line upon the paper. 

Upon the return of the engine 
cross-head the drum is revolved 
by a spring which is constantly 
held under tension. A section 
of the paper drum of the Rob- 
ertson-Thompson Indicator is 
shown in Fig. 13. 

In preparing to indicate an 
engine, then, we have two prob- 
lems to consider only ; one is to 
place the indicator in perfect 
communication with the cylin- 
der at each end, and the other 
is to rig a reducing motion that 
will give to the indicator in its reduced scale an exact repro- 
duction of the movement of the piston. Usually the indi- 




Fig. 12. Thompson 
Parau,ki, Motion. 




Fig, 



13. Paper Drum. 



Hawkins Indicator Catechism, 13 

INTRODUCTION. 

cator holes may be found plugged on removing the laggings. 
Most engine builders provide their engines for indication. 

In a perfect indicator the pencil should, by its vertical 
position upon the diagram, represent exactly the pressure 
beneath the indicator piston at any instant; and by its 
horizontal position, the point which the piston has reached 
in its stroke at the same instant. This is accomplished by 
the spring upon whose accuracy depends the correctness 
of its conclusions or records. To secure this accuracy, it 
is well to have the springs tested. All of the manufac- 
turers will make such tests of springs for purchasers, and 
the diagrams of the test may be kept as a record of the 
degree of accuracy of the instrument at that time. It is 
well also to have such tests made occasionally after the in- 
strument has been in use, and especially just before and 
after applying it to work of particular importance. The 
test consists of applying steam to the indicator piston at 
pressures increasing by equal amounts, say, for ordinary 
springs, five pounds. As each five pounds is reached a line 
is drawn upon the card, a standard gauge or, better, a mer- 
cury column being used to indicate the pressures. 

The movement of the pencil should be exactly propor- 
tional to that of the piston — a principal of operation that 
is closely followed by all makers of the instruments. 

Another quality of importance is the freedom from fric- 
tion that an indicator should possess in the greatest pos- 
sible degree. To make a test detach the piston and see 
that the pencil levers will drop freely and without any sus- 
picion of a catch from any position within the working 
range of the instrument. With the piston attached, but 
without any spring, raise the piston by taking lightly hold 
of the pencil, and work the pencil lever up and down 
through the full limit of its motion, feeling carefully for 
any interruption to its movement. Then raising the pencil 
nearly to the top of the paper-drum, cover the hole through 
which steam is admitted to the indicator with the thumb ; 

Note.— This test must be made with a dry instrument— hence, 
before beginning, wipe carefully. 



14 Hawkins Indicator Catechism. 

INTRODUCTION. 

when the pencil should sink slowly down through the whole 
range of its motion, but should drop instantly from any 
point upon the removal of the thumb. 

Do not get the piston too tight, through fear of its leak- 
ing. It has a whole boiler full of steam behind it part of 
the time, and a large volume always, and no noticeable dif- 
ference in pressure will result from any leakage which can 
take place unless the leakage is so excessive as to increase 
the pressure on top of the piston. 

On condensing engines the vacuum, as indicated by the 
indicator, may be materially reduced if the piston is too 
loose, and it is unpleasant and uncleanly to have too much 
steam and water leaking and spattering about the instru- 
ment. The piston which will sustain the test just described 
will be found tight enough without excessive friction. 

The line in which the point of the pencil moves should 
be exactly parallel with the axis of the paper drum, in 
order both that the pencil may bear upon the paper equally 
in all portions of its stroke, and that its vertical movement 
may be at right angles with the horizontal movement of 
the paper. 

If the line does not comply with these conditions, the 
natural inference will be that the pencil movement is 
incorrect, although the horizontal line may be thrown 
out by any vertical movement of the cylinder upon its 
spindle. 

Lost motion is usually a matter mpre of adjustment than 
of manufacture. Put a stiff spring into, the indicator, and 
carefully feel at the end of the pencil lever for any unre- 
strained movement. Should such be found, its cause 
should be searched for in the connection of the piston rod 
to the piston and pencil motion, through all the joints of 



NOTE. — An elaborate apparatus for drawing these lines automatic- 
ally as the mercury rises in the column is maintained by the United 
States Government at the New York Navy Yard, for testing and stand- 
ardizing the indicators used by the navy. 



Hawkins Indicator Catechism. 15 



INTRODUCTION. 

the parallel motion, in the fit of the collar which carries 
the mechanism, and if it cannot be corrected by adjust- 
ment without making the instrument too stiff to comply 
with the friction test above described, the instrument 
should be rejected. 

The above qualities are necessary to an indicator for 
accuracy. Other points, more in the nature of conveni- 
ences than essentials, but which may be well considered in 
selecting an instrument, are the comparative simplicity of 
changing springs, adjustment for height of atmospheric 
line, changing from right to left hand and vice versa^ ad- 
justing the drum-spring and leading pulley, attaching the 
indicator to the cock, etc. For holding the lead, the end 
of the pencil lever in some indicators is formed into a light 
steel quill of a size that will hold the lead firmly when 
forced through it. In other makes the end of the pencil 
lever is reinforced and threaded internally, the lead being 
screwed through it. 



HAWKINS' 



INDICATOR CATECHISM. 



QUESTIONS AND ANSWERS. 

QUES. What is the first thing important to be known 
relating to the Steam Engine Indicator? 
Ans. The name of its essential parts. 

QUES. What next is of importance ? 
Ans. To know the special terms, definition and " shop 
names " in ordinary use. 

QUES. Cannot the instrument be used without this 
knowledge ? 

Ans. Yes ; it can be done, but it is next to impossible. 






NOTE. — It is an unwritten law that each art, science, and mechani- 
cal contrivance has related to it certain words, phrases and definitions, 
which are known mainly and almost exclusively to those who practice 
the arts or vise the tools. In order to gain the necessary instruction in 
the shortest time and in the most thorough manner it is well for the 
learner to have already memorized and at his tongue's end those 
elementary shop names and definitions. 



Hawkins Indicator Catechism. ij 

QUESTIONS AND ANSWERS. 

QUES. Is the indicator more properly a machine or an 
instrument? 

Ans. It is an instrument because it is a device by which 
work is performed or anything is effected ; a machine or 
engine implies a much larger piece of mechanism. 

QUES. What are the special important uses of the indi- 
cator? 

Ans. It is used primarily to measure the power of the 
steam engine ; second, to show the quantity of steam used 
per horse power for a given time ; also, to indicate how to 
adjust the valve gear of the engine. 

QUES. What other uses can be named for which the 
instrument is serviceable? 

Ans. It shows the vacuum obtained by the use of the 
condenser and the relative pressure existing between the 
steam in the boiler and the pressure of the steam in the 
cylinder. 

QUES. What are the principal (four) parts of the indi- 
cator ? 

Ans. The cylinder, the spring, the piston with its con- 
nections, and the drum. 

QUES. Does the steam required to operate the indicator 
go to waste ? 

Ans. Yes ; in effect it is so much added to the per- 
centage of clearance of the cylinder. 



NOTE. — The indicator does no work, any more than a guide post ; 
it simply records on the diagram the work being performed by the 
engine. 



i8 Hawkins* Indicator Catechism. 

QUESTIONS AND ANSWERS. 

QUES. What parts of the instrument will have to be 
closely observed when diagrams are being taken ? 

Ans. i, The pencil levers, that they do not get bent ; 
2, the lead, which must not be too large, and always should 
have a fine round point ; 3, the drum spring, which must 
not be too slack nor too tight ; 4, the piston rod, which 
must not be too short nor too long, otherwise the pencil 
will travel either too high or too low on the card. 

QUES. What other parts should be looked after while 
indicating or preparing for indicating? 

Ans. Care should be taken that no lost motion is in 
the reducing mechanism and its connections, for this would 
produce serious error on the diagram. In adjusting the 
cord, it should not be made too long or too short, and, 
when putting the paper upon the drum, it should be 
placed smooth, so it will not offer any obstructions to the 
pencil. 

QUES. When piping up the indicator, what is there 
important to be guarded against ? 

ANS. No pipe chips, red lead or other foreign matter 
must be allowed to remain in the pipes, and when tapping 
apertures into the cylinder for indicator connections they 
must be so located that the piston will not obstruct the 
holes. 

QUES. How should the instrument be treated after 
use? 



Note. — Also, care should be taken not to allow the pencil to press 
too tightly upon the paper, which may produce unnecessary friction, 
and produce error in the final results. 



Hawkins Indicator Catechism. 19 

QUESTIONS AND ANSWERS. 

Ans. It should be cleaned, wiped dry, and oiled, so as 
to be ready for the next test. 

QUES. What about the springs? 

ANS. The springs are the most vital part of the instru- 
ment, and need particular attention. They must not be 
allowed to get rusty, otherwise they will be useless for 
accurate work. 

QUES. I§ there any other simple way of causing serious 
error in applying the indicator? 

ANS. Error is often produced by not shutting the indi- 
cator cock properly. It is not supposed to be pressed 
tightly into its sedt, as this would soon cut both plug and 
seat, and cause the cock to leak. Besides the steam pas- 
sage through the plug of the indicator cock, there is a small 
hole drilled at right angles to the steam passage, which 
communicates with a similar hole in the body of the cock ; 
now, when shutting the cock, the plug should be turned so 
that this hole will point toward the indicator cylinder, and 
thus open communication between the atmosphere and 
the cylinder of the instrument, and thus allow the atmos- 
pheric line to be drawn in its proper place. 

When opening the cock, this hole should be turned so 
that the steam will not escape through it. 

QUES. In indicator practice, what is meant by absolute 
pressure ? 

Ans. Absolute pressure is the pressure of the steam 
above a perfect vacuum. 

QUES. What is gauge pressure ? 



20 Hawkins Indicator Catechism. 

QUESTIONS AND ANSWERS. 

Ans. Gauge pressure, or pressure by gauge, is the 
boiler pressure, as indicated by the steam gauge, or the 
pressure per square inch of boiler surface above the atmos- 
pheric pressure. 

QUES. What is initial pressure? 

Ans. Initial pressure is the pressure in the engine cyl- 
inder as shown by the indicator, at the beginning of the 
stroke. The initial pressure is ordinarily below the gauge 
pressure, on account of the wire drawing in the connection 
between the cylinder and boiler. 

QUES. What is wire drawing? 

Ans. Wire drawing is a term used in describing the 
reduction of pressure caused by passing the steam air or 
gas through a narrow opening. 

QUES. What is the definition of mean effective pres- 
sure ? 

Ans. Mean effective pressure is the average of the 
pressures recorded by the indicator at different points of 
the stroke above the exhaust pressure. It is the pressure 
which would have to act upon the piston throughout the 
entire stroke to cause the engine to develope the same 
power as under the indicated conditions. 

QUES. What is terminal pressure? 

Ans. Terminal pressure would be the pressure at the 
end of the stroke, if the exhaust valve did not open before 
the piston comes a dead standstill. 



NOTE. — As in all engines the exhaust valve opens before the end of 
the stroke, the terminal pressure is never reached. 



Hawkins Indicator Catechism. 21 

QUESTIONS AND ANSWERS. 

QUES. What is back pressure ? 

ANS. Back pressure, or counter pressure, is the amount 
of pressure above the atmosphere during the exhaust 
stroke. The back pressure counteracts the forward move- 
ment of the piston, and therefore should be avoided. On 
an indicator diagram it is found by allowing the instrument 
to trace the atmospheric line after taking the diagram. 

QUES. What is meant by " ratio of expansion " ? 
ANS. Ratio of expansion is the entire cylinder volume, 
divided by the volume before cut-off. 

Ques. What does clearance mean? 

Ans. Clearance is the space included between the pis- 
ton at the end of the stroke and the cylinder head ; to this 
is added the volume of the steam ports. The clearance is 
generally expressed in percentage of the cylinder volume. 

QUES. What is saturated steam ? 

ANS. Saturated or dry steam is steam in a perfect gas- 
eous state. Any loss of heat will change its condition by 
partial condensation. 

QUES. What is superheated steam ? 
ANS. Superheated steam is such as is heated above the 
temperature of saturation. 

QUES. What is the difference between an indicator 
diagram and an indicator card ? 

Ans. The diagram is the outline traced by the pencil 
upon a card or paper, and a piece of paper becomes an 
" indicator card " when it is used to record one or more 
diagrams. A card often contains a diagram from both the 
head and crank ends of the steam cylinder. 



22 HAWKINS' INDICATOR CATECHISM. 



AN INDICATOR OUTFIT. 

An indicator outfit consists of the following articles : 

The indicator, or if a very accurate test is required, both 
ends of the cylinder have to be indicated simultaneously, 
and thus two instruments are needed. 

A good reducing motion, as preferably a pantograph or 
reducing wheel. 

The cord for connecting reducing motion to indicator. 

The indicator cards. 

Pencils. 

One three-way cock, or two straight-way cocks. 

Three or more springs, of different tensions. 

The corresponding scales for the springs. 

A bottle of pure machinery oil. 

The necessary wrenches, spanners, screw-drivers, etc., 
belonging to the indicator. % 

Planimeter. 



Note. — The original indicator, as first invented by Watt, consisted 
simply of a piston working in a cylinder against the resistance of a 
spring. The movement of the spring, due to the pressure of the steam 
on the piston, was shown by a pointer attached to the piston rod of the 
instrument, and pointing to a scale. Later, Watt added a board, on 
which was attached a piece of paper moving simultaneously with the 
piston of the engine ; a pencil was substituted for the pointer, and a 
card traced on the paper on the board. Watt did not use the paper 
drum, which was added by a contemporary and generally adopted, and 
substantially in this form the instrument remained until the introduc- 
tion of the Richardson Indicator. Richards added to the indicator 
Watt's parallel engine motion, and by multiplying the movement of 
the spring by using a lever, allowed a stifFer spring to be used. 



HAWKINS' INDICATOR CATECHISM. 23 



PREPARING THE INDICATOR FOR USE. 

In selecting a spring, aim to get as large a card as pos- 
sible without undue distortion. If a card be taken with a 
20 spring, an error of measurement of j^ of an inch would 
influence the results only one-fifth of a pound. With a 
50, spring the same error in measurement would represent 
a departure of one-half a pound. 

It is, therefore, advisable to have the area as large a* 
possible. 

On the other hand, the allowable movement of both the 
pencil and the drum is limited by the effects of momentum 
At high speeds a light spring and long movement of the 
drum would result in a diagram so distorted by the effects 
of momentum and inertia as to introduce errors much more 
serious than those that are likely to occur from inaccurate 
measurement of a smaller and more perfect diagram. The 
speed as well as the pressure will therefore have a bearing 
on the spring selected, and will also influence the selec- 
tion as between the standard size of paper drum which is 
used for moderate speeds, and the smaller drums which 
some of the makers supply for high-speed work. Some 
manufacturers furnish two sizes of drums, which may be 
used interchangeably upon the same instrument, adapting 
it to the highest and slowest speeds. 

In changing the spring, unscrew the head of the indi- 
cator, hold the carrying ring as shown in Fig. 14, and the 
piston and .spring may easily be disconnected from the 
moving parts and head. 



24 



HAWKINS' INDICATOR CATECHISM, 



PREPARING THE INDICATOR FOR USE. 

In some instruments the position of the atmospheric line 
is fixed ; in others it is adjustable, so that in indicating a 
non-condensing engine the base-line may be lowered, and 
the whole of the allowable movement of the pencil utilized 
for the height of the diagram. 




Fig. 14. 

The adjustment for height is effected by lengthening or 
shortening the distance between pencil lever and piston. 

It is frequently desirable, in condensing engines, to obtain 
the lower or condensing portion of the diagram on -a 
larger scale than that of the spring available with the initial 
pressures used. With an initial pressure that demands a 
60 spring, a realized vacuum of twelve pounds would be 
represented by a line only one-fifth of an inch below the 
atmospheric line, Fig. 15, giving a very small area to the 
condenser portion of the card. In order to obtain this area 



HAWKINS 1 INDICATOR CATECHISM. 



%* 



PREPARING THE INDICATOR FOR USE. 

upon a larger scale, giving increased accuracy of measure- 
ment, showing more clearly the points of release and com- 
pression, etc., springs of low tension are sometimes fitted 
with bosses or studs, which prevent their closing beyond 
a certain point, while they are free to extend to any 
amount. 




Fig. 15. 

In Figs. 15 and 16 are shown two diagrams, the first 
drawn to a 60 scale ; and beneath it the shaded portion of 
the diagram is shown expanded to a 10 scale. Notice how 
much more prominently the points of release and compres- 
sion are shown, on account of the more rapid vertical move- 
ment with the same horizontal movement ; and how much 
less an error of a few hundredths of a square inch in meas- 
uring the area of the condensing portion of the card would 
affect the result. 

Select a hard lead of good smooth quality and of small 
diameter, and use only a small piece at a time. At the end 
of the pencil lever, where the motion is greatest, the weight 
should be reduced to the smallest possible value. If 
pointed with a fine file and rubbed down with an emery 



26 HAWKINS' INDICATOR CATECHISM, 

PREPARING THE INDICATOR FOR USE. 

stick, such as is used for sharpening draftsmen's pencils, or 
a fine stone, it will wear longer and be smoother and more 
satisfactory than if whittled into shape. 

For lubricating the bearings of the instrument a light 
machinery oil should be used — one that will not gum or 
corrode. A small vial of such oil usually accompanies the 




Fig. 16. 

instrument, some makers furnishing porpoise oil, such as is 
used for clocks and watches. The piston, however, is better 
lubricated with cylinder oil, which must be absolutely free 
of grit. 

Filter the oil carefully and make sure that the can is 
perfectly clean ; a small particle of grit upon the piston of 
an indicator will not only throw the diagram into mislead- 
ing forms, but may scratch and injure both cylinder and 
piston to a serious degree. 

Use hard, tough smoothly calendered paper of a width 
sufficient to include the highest allowable pencil travel, and 
about an inch longer than the circumference of the barrel. 



HAWKINS' INDICATOR CATECHISM. 27 



REDUCING MOTIONS. 

In order to use the indicator, a means must be provided 
for moving the paper drum exactly in time with the engine 
piston. This movement is usually derived from the cross- 
head, and the appliance used to reduce the movement to 
that adapted to the paper barrel is spoken of as the " reduc- 
ing motion." 

The most simple expedient for this purpose is a lever 
suspended from the ceiling or other suitable support, and 
connected at its lower end with the cross-head in such a 
way that it will be swung back and forth as the engine 
makes its revolutions. The motion of the lever increases 
from nothing at the point of suspension to approximately 
the full stroke of the engine at the cross-head end, the 
amount of motion being directly proportional to the dis- 
tance from the point of suspension. A point midway of 
the lever would have a motion equal to one-half the stroke; 
one-quarter of the way from the point of suspension, one- 
quarter stroke, etc. 

In order to find the distance of cord-pin from the ful- 
crum of the lever, multiply the total length of the lever by 
the desired length of diagram, and divide by the stroke of 
the engine, all in inches. 

The total length of the lever is measured from the point 
of suspension to the point of attachment to the cross-head, 
and is variable in some of the arrangements to be shown. 
As the variation bears a small proportion to the total 
length, and the length of card is usually figured only to 
keep within the limits of the paper drum, especial refine- 
ment in this particular is unnecessary. 



28 



HAWKINS' INDICATOR CATECHISM. 



REDUCING MOTIONS. 

In order to get the full motion of the cord-pin, the cord 
must be led off in the direction of the pin's greatest move- 
ment, i. e. y at right angles to the lever when the lever is 
itself at right angles to the guides. It will be readily seen 
that if the cord were led off parallel to the lever, it would 
receive very little motion. It is desirable to avoid the use 
of leading pulleys, and Figs. 17 and 18 show two methods 
of accomplishing this ; the first by putting on a segment of 
a circle, called a brumbo pulley, having a radius equal to 




Fig. 17. 



Fig. 18. 



the distance from the fulcrum to the attachment of the 
cord, and so placed that the cord may be led straight to 
the indicator without running on to the corners of the seg- 
ment at the extremes of the stroke. 

In Fig. 18 a supplementary lever is added in such a 
position that when the main lever CC is at right angles to 
the guides the line AD will be at right angles to the cord 
when the latter is led in the desired direction. 



HA WKINS IN DIC A TOR CA TECHISM. 



29 



REDUCING MOTIONS. 

If a lever reducing motion is employed, the lever should 
not be less than twice the length of the stroke. 

The point of suspension of the lever should be directly 
over its point of attachment to the cross-head when the 
latter is in the center of its- stroke. 




{CLt6S. GGESEB-CO. CK. 07") 



Fig. 19. 



In Figs. 19 and 20 are shown two devices for reducing 
the motion of the cross-head. Fig. 19 represents the re- 
ducing motion manufactured by the Buckeye Engine 
Company, while the simple device in Fig. 20 can easily be 
made by any mechanic. 

A far better method of reducing the motion of the cross- 
head is the pantograph, two kinds of which are shown in 
Figs. 21 and 22, and their application can be seen in Figs. 
23 and 24. 

There is no patent upon the pantograph in either of 
these forms, and anybody who has tools and knows how 



Note. — In all motions of this kind there is a radical defect due to 
the fact, that while the cross-head moves in a straight line, any point 
on the lever swings through the arc of a circle. 



30 



HAWKINS' INDICATOR CATECHISM. 



REDUCING MOTIONS. 

to use them can make one for himself. The members are 
usually made of strips of hard wood, one and one-eighth by 
five-sixteenths of an inch, and sixteen inches between the 
pivoted points. 

Besides these devices there are a number of reducing 




]C\.rr.r,, GOi:5ER-CO,CIM.O | | 




Fig. 20. 

wheels on the market, one of which, called the "Victor" 
reducing wheel, is shown in Fig. 25. The cord that is 
wound upon the large wheel is attached to the engine 
cross-head, while the drum cord is wound upon a small 
pulley, which is in communication with the large one in the 
manner shown in Fig. 25. 

In Fig. 26 is shown the "Ideal" reducing wheel 
attached to the American Thompson indicator. 

Fig. 27 shows the attachment of the Ideal reducing 
wheel to a Bachelder indicator, and their application to the 
cylinder and cross-head of a Corliss engine. 

In Fig. 28 is shown the Houghtaling reducing motion, in 
connection with the Tabor indicator. 



HAWKINS' INDICATOR CATECHISM. 31 

REDUCING MOTIONS. 

This reducing motion is composed of a supporting base- 
piece K, provided with short standards that form bearings 
for the worm-shaft R, on which the flanged pulley O is 
rotated, the outer bearing being a pivot p, which receives 
the entire thrust of the shaft R, thus reducing the friction 
to a minimum. It is connected direct to the indicator 



Fig. 21. Pantograph. 

upon the projecting arm that supports the paper drum B, 
and the teeth of the worm-shaft R, mesh directly with the 
teeth on the spool g. Connected with the base-piece K is 
a spring case d y and on the extreme end of the worm-shaft 
R is a thumb-piece u* There is also secured upon this 
worm-shaft R, a collar, not shown in the illustration, 
through which a clutch-pin secured directly to the thumb- 
piece it slides. • 

The flanged pulley O runs freely and independently on 



32 



HAWKINS' INDICATOR CATECHISM. 



REDUCING MOTIONS. 

worm-shaft R, and has on its outside a clutch-shaped hub. 
To this pulley O is connected the actuating cord, which 
should encircle it a sufficient number of times to have its 
length when unwound a little more than equal the length 
of the stroke of the engine. The other end of the cord is 
secured either to the cross-head of the engine, to a standard 




Fig. 22. Pantograph. 



bolted to the same, or to any moving part that has an 
exactly similar motion, and must be connected in line from 
the pulley 0. 

Inclosed in the spring case d is a small, plain spiral steel 
spring which operates to return the pulley O back to its 
starting point, after it has been revolved in one direction 
by the forward movement of the engine cross-head. As 
this pulley O has an independent, rotating back and forth 
motion on the worm-shaft R, the necessity of unhooking 
the cord when the indicator is not being operated is entirely 
overcome. The paper drum B is rotated forward by the 



HAWKINS' INDICATOR CATECHISM, 



33 



REDUCING MOTIONS. 



pulley through its worm-shaft R, engaging with the 
worm-gear^, and in the opposite direction by the action of 
its own retracting spring. 



te 



■ura^ 



-g 




Fig. 23. Application of Pantograph. 



To operate this device, first select a pulley whose cir- 
cumference is from one-quarter to one-fifth the length of 
the engine stroke. 




Fig. 24. Application of Pantograph. 

In placing this pulley on the worm-shaft R, after remov- 
ing the clutch and its collar, care should be taken to have 
it set on the small projecting pin on the cover of the spring 
case d\ then replace the clutch collar and clutch, pushing 
the collar on to the shaft as far as it will go and holding it 
in place by the set screw. 



34 



HAWKINS' INDICATOR CATECHISM. 



REDUCING MOTIONS. 




Fig. 25. Victor Reducing Wheei,. 



Next, place the indicator in position and run out the 
loose end of the cord in a direct line with the pulley 0> to 
the point on the engine to which it is to be connected ; 




l ; ig. 26. Ideai, Reducing Wheei*. 



HAWKINS' INDICATOR CATECHISM. 



35 



REDUCING MOTIONS. 

then bring the cross-head of the engine to the extreme limit 
of the forward travel, and with one or two turns of the cord 
left unwound on the pulley. 




>4 
W 
W 

n 



c 

>— 
O 



p 
w 



« 

P 
(-( 

P 
12 



C 

< 

E 

P 

E 






bo 

S 



The spring should have sufficient tension to take in all 
the slack of the cord when on the return stroke. 



36 



HAWKINS' INDICATOR CATECHISM. 



REDUCING MOTIONS. 

When pulley O is running, motion to the paper drum B 
is obtained by pushing in the thumb-piece u, to which the 
clutch-pin is secured. When ready to take diagrams, after 
placing the paper on the drum 2?, it is first necessary to 
advance the drum away from its stop fully one-quarter 




Fig. 28. HOUGHTAUNG REDUCING MOTION. 

inch, which can be done by turning with one hand the 
nerled top-piece. While holding the drum in this position, 
with the other hand push in gently the thumb-piece u y to 
start the paper drum in motion. 

The motion of the paper drum can at any time be 
instantly stopped for removing the diagrams, by withdraw- 
ing the clutch thumb-piece u y or by turning the top thumb- 
piece; the latter method is the best. 



HAWKINS' INDICATOR CATECHISM. 37 



PIPING UP THE INDICATOR. 

The connection between the indicator and the steam 
cylinder of the engine must be as direct as possible, so that 
the same pressure that is acting upon the piston in the en- 
gine may at the same instant act upon the piston in the 
indicator. The steam is acting in the indicator exactly as 
it does in the cylinder, but its load is a spring, and the ten- 
sion of a spring is known ; so, if it is known how much the 
spring has been compressed, it will also be known what 
pressure the steam must have exerted upon it. 

All modern engines are tapped for the indicator; imt if 
there should be no provisions made, the holes should be 
drilled into the counterbore of the cylinder, and tapped 
for a half-inch pipe thread. 

Care should be taken that none of the drill-chips drop 
into the engine cylinder, and that the holes thus drilled 
are not obstructed by the piston. 

If a single indicator is employed, the connection is usu- 
ally made in the manner shown in Fig. 29. 

When this connection is used, the bends should be as 
easy as possible. The ordinary elbows are not the proper 
thing to be used ; but in Fig. 32 is shown a large turn 
angle valve, which gives a very easy course for the steam, 



Note. — Be very sure that the passage to the cylinder is free, and 
that the piston does not even partially obstruct it at the end of the 
stroke. The beginning of the stroke is when the indicator makes its 
quickest movement, and a choking of the passage will produce appar- 
ently unaccountable results. By throwing a ray of light into the hole 
tapped for the indicator, the directness of the passage can be ascer- 
tained. 



38 



HAWKINS' INDICATOR CATECHISM. 



PIPING UP THE INDICATOR. 

and possesses the advantage of allowing the piping to be 
cut off from the cylinder, when the indicator is not in use, 
thus reducing the clearance. 

A three-way cock should also be used, an example of 
which is shown in Fig. 33 ; this allows the indicator to 
be connected to either end of the cylinder, by a quarter 
turn of the handle. 




Fig. 29. 



In Figs. 30 and 3 1 are shown other ways of connecting 
the instrument, of which Fig. 30 is the better way, as it 
dispenses with the elbow, and should always be used if two 
instruments are employed. 

In putting up piping or connections for use with the in- 
dicator, no rfed lead or other mixture should be used, as it 
will be carried by the steam to the indicator cylinder and 
produce trouble. A few drops of oil on the thread is usu- 
ally all that is required. 

Particular pains should be taken to remove from all pipes 



HAWKINS' INDICATOR CATECHISM. 39 

PIPING UP THE INDICATOR. 

and fittings all dirt, scale and burr that can become de- 
tached and work into the cylinder. 

When the connections are all up, allow the steam to blow 
through them freely some time before attaching the instru- 
ment, to remove any scale or dirt that is liable to become 
detached. 




Fig. 30. 

In connecting the paper drum to the reducing motion, a 
fine, flexible, braided cord should be used, and here a good 
deal of attention has to be paid not to have the cord either 
too long or too short. 

With the indicator in position and the engine in motion, 
loop the cord between the fingers and put it over the pin 
or hook, drawing it up enough to set the paper barrel in 
motion and clear the stop. Now draw the cord carefully 
up until the barrel touches the stop on the outward stroke, 
then let it slip back until it touches very lightly on the 



40 HAWKINS' INDICATOR CATECHISM. 

PIPING UP THE INDICATOR. 

backward stroke. Midway between these two positions is 
where the point of the loop ought to be. Take back nearly- 
half as much cord as has been allowed to slip past, tie the 
loop, and the length should be pretty nearly right. Do 
not throw the tied loop over the pin, however, nor hook it 
on, until it has been first held against the pin or hook and 
tried for proper length with the engine in motion. 







Fig. 3*- 

The tension of the drum or barrel spring should now be 
seen to. When the engine is making its outward stroke 
this drum is put in motion, and, having mass, acquires a 
certain amount of momentum, so that when the piston 
arrives at the end of its stroke and the string stops pulling, 
the drum continues to move by reason of its momentum 
until its stored energy is absorbed by the spring. If a high- 
speed engine be run at a very moderate speed and an 
atmospheric line be drawn, then with the engine running at 



HAWKINS' INDICATOR CATECHISM. 41 

PIPING UP THE INDICATOR. 

governor speed if another line be drawn just above it, there 
will be found to be a difference in the length of the lines. 
This produces, of course, a distortion in the card, and can 
be reduced by tightening up the barrel spring. For high- 




Fig. 32. Long turn Angi<e Cock. 

speed engines this spring will have to be kept under con- 
siderable tension, but on slower-moving machines it may 
be let down, and should in all cases be run only tight 
enough to keep the barrel well under the control of the 
Cord. 




Fig. 33. Three-way Cock. 

The working parts are now to be arranged and the in- 
strument put together. The pencil lever must be fitted 
with a lead. Do not use any more lead than is necessary 
to hold firmly in the quill or stub. Any extra weight is 



42 HAWKINS' INDICATOR CATECHISM. 

PIPING UP THE INDICATOR. 

especially to be avoided at this point, where it has so much 
motion, and if allowed to stick out on the barrel side of 
the arm it furnishes a lever to work itself loose in the holder 
or to twist the pencil arm sideways in its bearings. Bring 
the lead to a fine round point, not sharp enough to catch 
in and scratch the paper. This is best done by finishing 
with a very fine file. Then let it stick through as little as 
possible, leaving a little stock for filing the point as it 
wears on the side toward the paper, and break it off short 
at the other side. 

In selecting a spring, be sure to get one stiff enough. 
Attach the spring selected in its position, being careful to 
screw everything up to its place, put a few drops of cylin- 
der oil on the piston, open the cock on the indicator and 
let the steam blow once or twice through the cylinder ; then 
put in the piston, and screw the instrument together. If it 
is a condensing engine, do not open the cock when that end 
is exhausting, or it will make more work for the air-pump 
than it can conveniently handle. 



HAWKINS' INDICATOR CATECHISM. 



43 



TAKING INDICATOR CARDS. 



When the instrument has been put together properly, 
open the cock and let steam into it, setting the piston and 
levers in motion, and press one finger lightly on the top of 
the piston-rod, to see if everything is working smoothly. 




Fig. 34. Drum-stop Device. 

If the least indication of gritty, scratchy action is felt, shut 
off the steam at once, take the instrument apart, and find 
the cause. 

The paper is put upon the barrel by wrapping it 
snugly around the drum at the top, bending it around 
and allowing the ends to project between the clips at the 
top ; then by taking the lower corners as they protrude 
between the clips between the thumb and forefinger, as 
shown in Fig. 42, the paper may be drawn down over the 
barrel as smoothly as a glove. An additional pinch near 
the top, and a squaring of the corners if they need it, will 
render the operation complete. 

Now turn on the steam and warm up the instrument. 
On non-condensing engines it is well to turn the cock so 
that the steam will blow out into the atmosphere until it 



44 HAWKINS' INDICATOR CATECHISM, 

TAKING INDICATOR CARDS, 
shows blue and dry. When the water has disappeared and 
the pencil is vibrating smoothly, the paper drum being in 
motion, hold the pencil lightly against the paper and allow 
it to trace the diagram. For ordinary purposes of exhibi- 
tion, showing the valve action, distribution, etc., one revo- 
lution is sufficient to hold the pencil on. To show the 
governor action, variation of load, etc., the pencil will have 
to be held on for a number of revolutions ; and when 
measuring power, the pencil should be allowed to pass 
from ten to twenty times over, and the average diagram 
measured. 

Turn the cock off and bring the pencil again to the paper, 
tracing the atmospheric line. It is not good practice to 
trace the atmospheric line first, as the indicator and spring 
are not then heated, and under the same conditions as 
when the diagram is taken. 

If there are more than one card to be taken, it is neces- 
sary to stop the drum while removing the card from the 
clips ; this is done in some cases by making the cord in 
two lengths, and unhooking, whenever the drum is to be 
stopped. 

In Fig. 34 is shown a device, attached, if desired, to the 
Robertson-Thompson indicator, which enables the drum 
to be held with the spring under tension, while the paper 
is being removed. The slack of the cord is meanwhile 
taken up by a fine rubber band attached to the cord. 

In Fig. 35 is shown another attachment for this pur- 
pose, manufactured by the Ashcroft Mfg. Company, for 
stopping the drum without unhooking the cord. 

It consists of an arm attached to a part of the indicator 
by the 3crew. A slide is adjustable on the arm, and upon 



HAWKINS' INDICATOR CATECHISM. 45 

TAKING INDICATOR CARDS. 

it there is mounted a cord pulley for directing the actuating 
cord around the paper drum of the indicator. This slide 
can be instantly secured in any desired position on the arm 
by the thumb nut and washer. 

The manner of connecting and operating the attachment 
is as follows: the actuating cord from any ordinary form of 



Fig. 35- Drum-stop Device. 

reducing motion connected with the engine is passed 
around the cord pulley, thence on the paper drum of the 
indicator. 

When the slide is at its inner position no motion will be 
transmitted to the paper drum ; but by taking hold of the 
thumb-nut and moving the slide outward on the arm, it 
will cause the paper drum to rotate back and forth in the 
usual way while taking a card. 

At any convenient position on the actuating cord there 
is superposed a rubber band for the purpose of taking care 



46 



HAWKINS' INDICATOR CATECHISM. 



TAKING INDICATOR CARDS. 

of any slack in the cord when the slide is at its extreme 
inner position and paper drum at rest, thus avoiding any 
unhooking of the actuating cord during the time of operat- 
ing the indicator in making tests. 




Fig. 36. Electrical Indicator Attachment. 



If two or more indicators are used at once, it is desirable 
to set the pencils on the drums at practically the same 
moment. To do this there are several devices on the 
market, some of which are operated by an electromagnet. 
When the operator desires to allow the pencils to touch 
the cards, he presses a button, which causes the magnet- 
ized poles of the magnet to attract an armature attached 
to the carrying ring of the indicator. 

Fig. 36 illustrates this electrical attachment as applied to 
the Tabor indicator. 






HAWKINS' INDICATOR CATECHISM, 47 

TAKING INDICATOR CARDS. 

The attachment consists of a magnet support S, which is 
clamped to the body of the indicator and held in place by 
the set screw E. 

A magnet M is secured to the support, also binding 
screws C and spring D. 

An armature A is mounted on the rod B, and adjusted 
to coincide with the magnet M, and then secured to the 

A 



Fig. 37- 

rod B by the small set screw in the armature for that pur- 
pose. The rod B is screwed into the upright on the swivel 
plate of the indicator, and any movement of the armature 
A produces a similar movement of the pencil toward or 
from the paper drum. 

The spring D is for the purpose of holding the armature 
within the field of the magnet before the current is estab- 
lished, and also to quickly release it when the current from 
the battery is broken. 



48 



HAWKINS' INDICATOR CATECHISM. 



TAKING INDICATOR CARDS. 

Fig. 37 represents Sargent's Electrical Attachment, and 
consists of an electromagnet, A> which is supported by a 
bracket, B, which also secures it to the indicator plate. 
Binding posts, C C, are attached to the same bracket. The 
armature, D y is opposed to the magnet by a spiral spring 
in the centre of the coil, the tension of which is adjustable 
by means of a screw, E, at the back of the magnet. The 
movement of the armature outwardly is limited by two 




Fig. 38. 



screws, a and 2. To the armature is secured a small latch 
or hook, F, which is free to work vertically and engage 
with a screw-eye inserted in the arm A. The thumb-screw 
G t is for fastening the attachment to the plate of an 
indicator through a hole therein. 

Fig. 38 represents the Circuit Closer, and is designed to 
operate the electrically connected indicators, by closing the 
circuit through them, when the stylue or marking point is 
put against the paper on the drum of the indicator, to 
which it is attached. This enables the engineer making 



HAWKINS' INDICATOR CATECHISM. 



49 



TAKING INDICATOR CARDS. 

the test to control one of the indicators directly by hand, 
and by its use one Sargent attachment is dispensed with. 

It consists of a bracket, H, with a tubular projection, /, 
fastened to it, which contains the circuit closing mechan- 
ism. It is attached to the indicator plate by the thumb- 




Fig. 39- 



Fig. 40. 



screw, y, in precisely the same way that the magnets are 
to the other indicators, and is electrically connected in the 
same manner through the binding posts, K K. 

Fig. 39 shows a Crosby indicator fitted with a Sargent 
Electrical Attachment. 

Fig. 40 shows a Crosby indicator fitted with a Circuit 
Closer. 

In Fig. 41 is shown a pneumatic device, manufactured 
by Robertson & Sons, the operation of which can be clearly 
seen in the illustration. By squeezing the ball the pencil 
is caused to touch the drum. 



50 



HAWKINS' INDICATOR CATECHISM. 



TAKING INDICATOR CARDS. 

When finished indicating, remove the spring, piston, 
etc., from the indicator, and allow the steam to blow 
through the cylinder once or twice. Unscrew the spring 
from the piston and cap, dry it thoroughly, and wipe it 
clean. The springs are the vital part of the instrument. 
Upon their accuracy the value of all the work depends. 
Too much pains cannot be taken to have them perfectly 
accurate when bought, to keep them from deteriorating by 
rust or otherwise, and to ascertain their condition from 
time to time. 




Fig. 41. Pneumatic Indicator Attachment. 






Wipe up and clean the levers, oiling the joints, and you 
will find the instrument all ready for application next time. 
When the lighter parts have been attended to, the main 
body of the indicator will be found to be quite dry, from 
having the steam blown through it, and may be cleaned 
like the rest and put together. 






HAWKINS' INDICATOR CATECHISM. 51 




Fig. 42. 



52 HAWKINS' INDICATOR CATECHISM. 



THE INDICATOR DIAGRAM. 

In Fig. 43 is shown a theoretical diagram, which would 
be traced by the indicator pencil, if the action of all the 
different operations should be perfect. 

This, however, does not occur in practice, as it takes 
time for the valve to open, and to cut off the steam : thus 
the corners of the diagram cannot be as sharp as in Fig. 
43, also the expansion line can never be as perfect, on 
account of the cylinder condensation and re-evaporation. 




Fig. 43. Idkai, Diagram. 

The outlines of an indicator diagram represent six dif- 
ferent operations, which are indicated by different lines 
made by the pencil, and are partly due to the steam pres- 
sure acting upon the indicator piston, and partly due to 
the motion of the cross-head and the corresponding revolv- 
ing of the drum. 



HAWKINS' INDICATOR CATECHISM. 53 

THE INDICATOR DIAGRAM. 

These lines are named as follows: I, admission line ; 2, 
steam line ; 3, expansion line ; 4, release line ; 5, exhaust 
line ; and 6, compression line. 

To these may be added the atmospheric line. 

The tracing of an indicator card is effected in the follow- 
ing manner: 

Steam enters the indicator cylinder, and, forcing the 
pencil upward on the drum, causes it to make the admis- 
sion line. This happens at the beginning of the stroke. 

The cross-head now begins to move outward, revolv- 
ing the drum, while the pencil is held up by the steam 
pressure ; the steam line is thus drawn until the point 
of cut-off js reached, when the valve cuts off the steam 
supply. As the cross-head still continues to move, the 
steam beyond the piston is expanded and its pressure re- 
duced, which allows the indicator spring, previously held 
under tension, to force the pencil downward ; but as, on 
account of the motion of the drum, it cannot descend in a 
straight line, it traces a curve, which records the steam 
pressure at all different points of the stroke after cut-off. 
This curve is termed the expansion line. 

When the cross-head nearly reaches the end of the 
stroke, the exhaust valve opens, causing the steam to rush 
out of the cylinder and the indicator pencil to drop, mak- 
ing the release line. 

The cross-head now begins on its return stroke, and the 
drum spring revolves the drum in the opposite direction. 

The pencil, being at a height corresponding with the ex- 
haust pressure, now marks the exhaust line, which may be 



Note. — If there should be no back pressure, or vacuum, the exhaust 
line would be at equal height with the atmospheric line. 



54 



HAWKINS' INDICATOR CATECHISM. 



THE INDICATOR DIAGRAM. 

either above or below the atmospheric line, according to 
whether the engine is running with back pressure or con- 
densing. 

At a point near the end of the exhaust stroke the ex- 
haust valve closes ; and the remaining steam in the cylinder, 
having no passage to escape, is compressed by the advanc- 
ing piston, thus raising the pressure, and also the indicator 
pencil, which now draws the compression line. 




HAWKINS' INDICATOR CATECHISM. 55 



THE ADMISSION LINE. 

The admission line shows the manner in which steam is 
admitted to the cylinder. Under normal conditions, ad- 
mission takes place suddenly while the piston is practically 
standing still at the end of the stroke, resulting in a straight 
line perpendicular to the atmospheric line, into which the 
compression line merges, as shown at A, Fig. 44. 

In order that the admission line may be thus erect, it is 
necessary that the steam valve shall be open so as to admit 
the full pressure before the piston begins to move away ; 
and this involves the question of lead, or the amount 
of opening which the valve has when the engine is on the 
center, and which, for many reasons, it is desirable to keep 
as small as possible, and yet allow the admission line to be 
perpendicular. As the steam valve is allowed to become 
late in opening, and the piston gets into motion before the 
steam is admitted, the admission line begins to curve 
inward, as at B and C, the leaning tendency increasing as 
the line progresses and the motion of the piston becomes 
faster. At D is shown a peculiar admission line on a dia- 
gram of a slide-valve engine, the eccentric of which had 
slipped so as to make the whole valve motion late. The 
exhaust closure being late as well as the steam opening, 
the compression was entirely cut out, and the back pres- 
sure line b continued straight up to the end of the stroke. 
When the piston commenced its return stroke the steam 
valve had not opened. The exhaust valve had by that 
time closed, the space between the cylinder head and the 
retreating piston was entirely shut in, and as the piston 



56 



HAWKINS' INDICATOR CATECHISM. 



THE ADMISSION UNE. 
moved away a vacuum was created, running the pressure 
down toward a, as is shown by the arrow. At a the steam 
was admitted suddenly and the admission line ran up, leav- 
ing the loop on the heel of the diagram as shown. 




The admission line may lean in, however, from another 
cause than that of the steam valves being late, as at E. 
The natural inference from the appearance of the diagram 



HAWKINS' INDICATOR CATECHISM. 57 

THE ADMISSION LINK. 

would be that the engine was late all around ; but the fact 
is that the steam valve has plenty of lead, and opens before 
the return stroke is completed. The exhaust valve is so 
late that it not only does not close for compression, but 
does not close until the piston has got well started on the 
forward stroke, so that the steam is blowing right through 
into the exhaust and cannot keep the pressure up. As the 
exhaust closes, however, the pressure is increased, but the 
piston is moving away so rapidly that the line never be- 
comes erect. 

The amount of compression has a great deal to do with 
the appearance of the admission line. The effect show r n 
at F is a very common one, produced by the pressure run- 
ning up by compression to the point and falling away as 
the piston starts back before the steam valve opens, forming 
the loop. A more aggravated case of the same action is 
shown at G. This loop assumes all sorts of forms, accord- 
ing to the relations of the compression and admission, and 
the proportions of the openings and the piston speed ; and 
it may even form when the steam valve opens promptly, 
by excessive compression, as is frequently seen on diagrams 
from the ordinary type of single valve, high-speed engines 
with shaft governors, where the compression is increased 
as the load diminishes, resulting in admission lines like 
those shown at H and /. In the first of these the pressure 
is so low that the compression line extends above it, and 
when the steam valve opens, there is an escape of steam 
from the cylinder and the pressure is lowered to that at 
which the steam will flow from the chest. The appearance 
at / is produced when the engine is lightly loaded, so that 
the compression is very considerable. 



58 HAWKINS' INDICATOR CATECHISM. 

THE ADMISSION LINK. 

Just as a tardy action of the steam valve results in pro- 
ducing an inward leaning of the admission line, so a too 
early opening of that valve will result in the production of 
a line which leans outward, as shown at K. 

Any engine that is in line and properly adjusted in the 
connections, should run at the speed for which it is de- 
signed better with enough lead to bring the admission line 
upright than it does with more. 



NOTE. — A sharp point at the top of the admission line is usually an 
indication of too much lead, and it will be found to result in smoother 
running if the corner is just given an indication of rounding, as at A. 
The projection is due to the fling of the moving parts carrying the 
pencil above the point due to the pressure. 



HAWKINS' INDICATOR CATECHISM, 59 



THE STEAM LINE. 

The steam line of the indicator diagram indicates what 
percentage of the boiler pressure is realized in the cylinder, 
and how well this pressure is maintained up to the point 
of cut-off 




Fig. 45. Examples of Steam Lines. 

In a really good diagram the steam line will appear about 
as at A, Fig. 45 — approaching, in its height above the at- 
mospheric line, the distance indicated by the boiler pres- 
sure laid off to the same scale as that of the spring with 
which the diagram is taken, as shown by the dotted line, 
and remaining horizontal, or very nearly so, up to the point 



Note. — It is absolutely impossible to maintain in the cylinder the 
same pressure that is carried in the boiler, although with short connec 
tions, ample passages, and low-piston speeds a very large percentage 
can be realized. 



60 HAWKINS' INDICATOR CATECHISM. 



THE STEAM LINE, 
of cut-off. When the connecting pipe and passages are 
small for the piston speed and diameter, the steam line 
falls away as at B y the difference between the beginning 
of the stroke, and a point near cut-off being shown by a 
and b. 

The steam line shown at C is often met with on engines 
having a large steam chest and small steam pipe— the steam 
chest in this case acting as a reservoir, and allowing the 
steam in the cylinder to almost equal boiler pressure at the 
commencement of the stroke; but if the steam pipe be 
small, this pressure cannot be kept up when the piston is 
advancing. 

Diagrams are sometimes met with which have no steam 
line, the load being so light that the expansion of the steam 
in the clearance is sufficient to keep the engine in motion. 
In this case the expansion line meets the admission line at 
a point, as at D, Fig. 45. 

The shape of the steam line is often modified by the ad- 
mission, and it will be readily understood that it is difficult 
to say when the one leaves off and the other begins, under 
frequently occurring conditions. 



HAWKINS' INDICATOR CATECHISM. 61 



THE EXPANSION LINE. 

In all engines in which any pretension is made to 
economy, steam is used expansively, the supply being 
cut off at some point in the stroke, determined either 
automatically by the governor or positively by the valve. 
By this means the piston is urged not only while there 
is a direct draught of steam from the boiler, but by the 
expansive force of the steam in the cylinder after this 
draught has ceased. 

The expansion curve is often found to be wavy — a fact 
generally due to the indicator piston fitting too tight, 
which will allow it to bind, thus working in jerks instead 
of steadily. 

A gas in expanding varies in pressure inversely as its 
volume ; and steam follows this law with sufficient accuracy 
to make its application to the indicator diagram and to 
engine practice of value. 

Thus if steam should be cut off at % of the stroke, the 
pressure in the cylinder would be reduced to % when the 
piston reaches y 2 stroke, }i when the piston reaches ^ 
stroke, etc. 

If the steam should be a gas, whose volume is not affected 
by the temperature of its surroundings, this k.w would hold 
true ; but as the steam upon entering the cylinder will con- 
dense, its pressure falls more rapidly than due to expan- 
sion, until a point is reached where the temperature of the 
steam equals the temperature of the cylinder walls, and 
from thence the condensed steam will be re-evaporated, 



62 HAWKINS' INDICATOR CATECHISM. 

THE EXPANSION LINE. 

because the metal of the cylinder is hotter than the steam. 
Thus it will be understood, that the true expansion curve 
never equals the theoretical curve. 

It falls below the theoretical curve at the first stages of 
expansion, and above it, crossing it at some point in the 
stroke, at a later stage. 

Also, that the steam in the clearance space will affect 
the expansion, as it is filled with steam during admission, 
and all this steam expands with the steam that filled the 
cylinder volume before cut off, without the clearance vol- 
ume being changed during expansion. 



HAWKINS' INDICATOR CATECHISM. 63 



THE RELEASE LINE. 

The proper appearance of the release line would be as 
at A f Fig. 46, the release occurring early enough to allow 
the pressure to fall nearly or quite to the line of counter- 
pressure by the time the end of the stroke is reached. 
If the release is delayed until the end of the stroke the 
appearance will be more like that indicated at B. If the 
pressure could be carried to the end of the stroke and im- 
mediately reduced to the line of counter-pressure, as indi- 
cated by the outline of the shaded space, it would be 
advisable to retain the full area; but since some area must 
be lost here in expelling the exhaurt, it is better that it 
should be above the diagram at A than below as at B. 
When the piston is approaching the end of its stroke, it 
has come to be a question of stopping it and sending it in 
the other direction. To do this smoothly, compression is 
applied on the other side of the piston, and obviously there 
is no object in keeping up the forward pressure, as at B. 

It is therefore better to let the pressure fall off, as at A, 
assisting instead of opposing the compression in bringing 
the moving parts quietly to rest, and by this early release 
removing the back pressure represented by the shaded por- 
tion at B y so that the piston encounters less resistance in 
starting upon its backward stroke when it is an .object to 
get it in motion. 

The difficulty of attaining this result on most engines is 
that where the lap is removed from a valve to cause it to 
open early and give an early release, this very lack of lap 
retards the closure and does not give sufficient compres- 



64 HAWKINS' INDICATOR CATECHISM. 

THE RELEASE LINE. 

sion. On the Corliss valve this may be corrected by setting 
the eccentric ahead, making both release and compression 
earlier ; but disadvantages attend upon too great an angular 
advance of the eccentric, in the way of shortening the 
range of cut-off, and the advantages of the valve motion in 
quick movement at admission, so that it is often necessary 




Fig. 46. Examples of Release Lines. 

to divide the difference and compromise upon a point like 
that shown at C. The benefit of an early release is very 
apparent when a condenser is used ; for, with an early re- 
lease and a prompt realization of the vacuum, as at D, the 
largest possible percentage of the load is thrown upon the 
condenser, while a tardy release and a dragging action of 
the steam in leaving the cylinder results in the loss of a 



HAWKINS' INDICATOR CATECHISM. 65 

THE RELEASE LINE. 

large area in the vacuum portion of the diagram, as shown 
by the shaded portion of E, Fig, 47, calling for a later 
cut-off and more steam. 

When the cut-off is late, more steam is admitted and has 
to be expelled ; the appearance will then be more like G y 
Fig. 47. Between this and the point shown at F, Fig. 48, 
there may be any variety of shapes, according to the 




Fig. 47. Examples of Release Lines. 

terminal pressure and setting of the valves. When the 
steam is cut off so early that the expansion extends below 
atmospheric pressure, or the pressure against which the 
engine is exhausting, the release line will be like that shown 
at H y Fig. 49. 

Here at the moment of release the pressure in the ex- 
"iaust pipe. is greater than that in the cylinder, and when 
the valve is opened at a, Fig. 49, there is an inrush of the 



66 



HAWKINS' INDICATOR CATECHISM. 



THE RELEASE UNE. 

previously exhausted steam, raising the pressure to the 
counter-pressure line. This condition is apt to cause a dis- 
agreeable slamming of the exhaust valve, which is lifted 
from its seat when the pressure in the cylinder becomes 
less than that beneath the valve, and is slammed closed 
again when steam is admitted. It may be stopped by 
throttling the initial pressure so that the lessened expan- 
sion does not cause a loop. 




Fig. 48. 

During the formation of this loop the pressure urging 
the piston forward has been less than that against which 
the piston moves, the forward motion continuing only by 
reason of the momentum of the fly-wheel and moving parts, 
so that the area of the loop represents just so much work 
exerted against the piston, and must be subtracted from 
the other area of the diagram to get at the effective work. 




Fig. 49. 



HAWKINS' INDICATOR CATECHISM. 67 



THE EXHAUST LINE. 

The pressure upon the piston during the forward stroke 
is represented by the steam and expansion lines ; the pres- 
sure in the same end of the cylinder during the backward 
stroke is represented by the exhaust, counter-pressure, or 
back-pressure line, as it is variously called. Obviously an 
engine will be doing the greatest amount of work when the 
pressure urging the piston forward is greatest and the 
retarding effect of the back pressure is least. 

If at the end of the stroke the steam has been expanded 
to atmospheric pressure in a non-condensing engine, there 
will be no immediate outrush of steam from the cylinder, 
because there is no greater pressure in the cylinder than 
that of the atmosphere into which the steam must flow. 
The steam must therefore be pushed out by the piston, 
and the resistance to its movement will depend upon the 
length and directness of the exhaust pipe, as well as its size. 

The compression of the steam by the piston pushing it 
out of the cylinder against the resistance to flow through 
the pipes and passages, will show on the indicator diagram 
in raising the line of counter-pressure above the atmospheric 
line. 



Note. — The actual tendency of a piston to move depends on the 
difference in pressure upon its two sides. If there were 30 pounds 
pressure in both ends of the cylinder at once, the piston would not 
move any more than though there were no pressure at all. If there 
were 30 pounds pressure on one side and 15 pounds on the other, the 
force with which the piston would tend to move would be the same as 
though there were 15 pounds on one side and nothing on the other. 
In other words, the effective pressure is the unbalanced pressure, or 
the difference in pressure between the two sides. 



68 



HAWKINS' INDICATOR CATECHISM, 



THE EXHAUST LINE. 

In a well-proportioned engine at moderate piston speeds, 
and exhausting through a short and ample exhaust pipe, 
this moving pressure will not be noticeable with an ordi- 
nary spring, and the line of counter-pressure will merge 
into the atmospheric line. In less advantageous circum- 
stances, however, the back-pressure line will be elevated 
above the atmospheric line. 

Sometimes a card is found where the back-pressure line 
starts in well enough, but makes a gradual rise toward the 
center of the diagram, falling again as the stroke is corn- 




Fig. 50. 

pleted, as in Fig. 50. This is caused by too much inside 
lap on a slide valve narrowing up the exhaust passage as 
the center of the stroke is reached, where the piston, 
and consequently the steam, has the greatest velocity. 
The same effect may be produced upon a Corliss engine. 
It is also found where a pair of cylinders working on cranks 
set at 90 exhaust into the same pipe, the release of one 
cylinder occurring practically in the middle of the stroke 
of the other and the efflux of steam into the pipe causing 
a rise of pressure. 






HAWKINS INDICATOR CATECHISM. 69 



THE COMPRESSION LINE. 

The object of compression is initially to furnish a cushion 
or gradually increasing resistance, in order to bring the 
moving parts to rest and change the direction of the push 
upon them without the shock which would follow upon the 
sudden opening of the valve. 

Compression is the inverse or opposite of expansion. In 
making the expansion line the volume of steam admitted 
up to the point of cut-off is increased in volume, the pres- 
sure falling in an inverse ratio. 

In compression the volume of steam inclosed when the 
exhaust valve closes is diminished in volume with a con- 
sequent increase in pressure ; and in this case, too, the 
product of the volume and pressure is constant. 

If there is any lost motion in the bearings, and the mov- 
ing parts have not been cushioned, there will be a heavy 
thump when the steam valve opens. 

In condensing engines, where the exhaust pressure has 
been reduced to nearly a perfect vacuum, the exhaust valve 
must close much earlier than in a non-condensing engine, 
in order to obtain enough compression. 

If a perfect vacuum could be obtained, so there would 
be no steam left in the cylinder, compression would not be 
possible. 

A perfect vacuum, however, cannot be obtained in prac- 
tice with a condenser. 

Aside from its cushioning effect there is another advan- 
tage to compression in reducing the loss from clearance, as 
the clearance space is filled with steam that otherwise 
would be wasted. 



70 HAWKINS' INDICATOR CATECHISM. 

THE COMPRESSION LINE. 

Where there is no expansion the steam required to fill 
the clearance space is a dead waste. With a cut-off engine 
it gets a chance to expand with the other steam, and does 
some good ; but still there is a saving by compression, and 
theoretically by compression up to the initial pressure. 

When the engine is of a type in which the compression 
is constant, as in four-valve engines, the best results will 
be attained under normal loads by having the compression 




Fig. 51. 

round up nicely into the admission line, as at a. Fig. 51, 
meeting the perpendicular line at about one-third of its 
height. This will require a different setting of the exhaust 
valve for different heights of the counter-pressure line. 

At b is shown excessive compression, the pressure run- 
ning up above that in the steam chest, so that when the 
valve opens for admission, steam flows from the cylinder 
to the chest and the pressure falls. A form of compression 



HAWKINS' INDICATOR CATECHISM 71 

THE COMPRESSION LINE, 
line often met with is shown at c, where the pressure, 
instead of continuing upward along the dotted curve, falls 
away as shown. When this occurs you must look for some 
cause for the reduction of pressure, and you will generally 
find it in a leak. As the piston approaches the end of its 
stroke its movement becomes very slow. The volume of 
steam involved is small and growing smaller, and if there 
is even a slight leak in the exhaust valve, drip valve, or 
piston there will come a time when the volume of steam 
discharged through the leak will equal the volume gen- 
erated by the movement of the piston in the same time. 

If the pressure of the outrushing steam is kept constant 
by the advancing piston. The line will have the appear- 
ance as shown at d. 




Fig. 52. 

If the leak should be so excessive that the advancement 
of the piston is not able to compress the steam fast enough 
to keep up the pressure, the compression line will fall away 
as at e. A diagram, where this occurred, is shown in Fig. 
52, where the compression line dropped down to A when 
steam was admitted. 

In this case the leakage was in the piston ; and as the 
pressure on the other side of the piston decreased, the 
leakage increased, on account of the greater difference in 
pressure on both sides of the piston. 



72 HAWKINS" INDICATOR CATECHISM. 



THE ATMOSPHERIC LINE. 

The atmospheric line is drawn after the diagram is com-, 
pleted, and the steam connection between the indicator 
and steam cylinder cut off. The atmospheric pressure is 
acting on both sides of the indicator piston, allowing the 
spring to expand into its original shape, thus indicating 
atmospheric pressure. 

In closing the indicator cock, care should be taken to 
close it so that the small drip-hole, drilled into the plug at 
right angles with the steam passage, opens communication 
between the atmosphere and the indicator ; otherwise an 
error may occur. 



THE LINE OF PERFECT VACUUM. 

The line of perfect vacuum would be the line which is 
drawn below the atmospheric line, 14.7 of a pound, meas- 
ured with the scale, which corresponds with the spring used 
in taking the diagram. 



HAWKINS' INDICATOR CATZCHlSM. 73 



THE CLEARANCE LINE. 

The percentage of clearance of an engine can be found 
by setting the engine on the center, and filling the clear- 
ance space with water, which must be carefully measured. 

The position of the cross-head must now be marked on 
the guide, and the engine moved off the center. 

Next pour an equal amount of water into the cylinder, 
on the same end as it took to fill the clearance space, and 
move the engine toward the same center as before, until 
the water is just beginning to run over, wherever it has 

been poured in. 

Now mark the position of the cross-head again, and 
measure the distance between the marks. 

The ratio of this distance to the whole stroke is the 
ratio of the clearance volume to the whole cylinder volume. 
Thus the percentage can be found by multiplying the 
length of the stroke in inches by ioo, and dividing by 
distance between the marks on the guide, also in inches. 

If it is desired to mark a clearance line on an indicator 
diagram, erect a line perpendicular with the line of perfect 
vacuum, at such a distance from the extreme point of the 
diagram on the admission side that this distance is the 
same fraction of the length of the diagram, as the distance 
between the marks on the guide is of the whole stroke. 
This is shown in Fig. 43. 



74 HAWKINS' INDICATOR CATECHISM. 



FIGURING STEAM CONSUMPTION BY 
THE DIAGRAM. 

Besides recording the condition and internal adjustment 
of the engine, the diagram as well as the horse power is 
used in figuring the steam consumption of the engine. 

In figuring the steam consumption, the cylinder volume, 
as well as the clearance volume, has to be known. The 
clearance volume can be found by filling it with water 
that has been previously measured ; this will enable the 
operator to find the number of cubic inches contained in 
the clearance space. 

The cylinder volume is found by the following rule : 

Square the piston diameter and multiply by .7854. 

Multiply the result by the stroke in inches and divide by 
1728. The result will be the cylinder volume in cubic 
feet. 

The steam consumption of an engine generally is ex- 
pressed in pounds per hour, and is computed in the follow- 
ing manner: 

1. Measure the pressure indicated by the expansion line 
at a point near the point of release, above the line of abso- 
lute vacuum. (Measure with the scale, which corresponds 
with the spring used in taking the diagram.) Find the 
weight of a cubic foot of steam at that pressure, in the 
accompanying table, and multiply this by the cubic capacity 
of the cylinder, plus the clearance volume, all expressed in 
cubic feet. 



HAWKINS' INDICATOR CATECHISM. 75 

FIGURING STEAM CONSUMPTION BY DIAGRAM. 

Instead of using the full length of the stroke in figuring 
the capacity of the cylinder, the piston area should be 
multiplied by a portion of the stroke, up to the point where 
the steam pressure has been measured. 

The result is the number of pounds of steam (by weight) 
it takes to fill the cylinder for each stroke. I. 

This would be correct if there should be no compression ; 
for as the compression is accomplished with the steam 
remaining in the cylinder from the exhaust stroke, it has 
to be deducted from the result obtained. 

Measure, with the same scale, the pressure above a per- 
fect vacuum at the point of highest compression, find the 
weight of the steam at this pressure in the accompanying 
table, and multiply this by the clearance volume. The 
result is the weight of steam remaining in the cylinder from 
the previous stroke. II. 

Subtract product II from product I, and multiply by 
twice the number of revolutions, and by 60, 

The result is the weight of steam, in pounds, that the 
engine consumes per hour; and by dividing this by the 
horse power, the steam consumption per hourly horse 
power is readily found. But this holds true only where 
there is no leakage, or outward radiation. 

Note. — The tables giving the weight of a cubic foot of steam at 
various pressures are to be found on pages 146-149, 5th column of 
tables. 

Example : Steam at 100 lbs. (absolute pressure) weighs .2307 lbs. per 
cubic foot (i. e., nearly % lb.), while at 140 lbs. it weighs .3162 lbs. 
(i. e. , nearly y^ of a lb ) 



76 



HAWKINS' INDICATOR CATECHISM. 



REVOLUTION COUNTERS. 

In high-speed engines it is difficult to count the number 
of revolutions ; hence a revolution counter, as in Figs. 53 
and 54, is employed. 

These possess the advantage of recording the revolu- 
tions made for any length of time, and during indicator 
tests of importance and of long duration, they are almost 
indispensable. 




Fig. 53. Revolution Counter. 




Fig. 54. Revolution Counter. 



Note. — The revolution counters shown are manufactured by the 
American Steam Gauge Company, of Boston, Mass. 



HAWKINS' INDICATOR CATECHISM. 



77 



REVOLUTION COUNTERS. 




Fig. 55- 

The above cut, Fig. 55, illustrates the Crosby locomo- 
tive counter — a counter designed particularly for use on 
locomotive and high-speed engines. The arm which 
moves the ratchet is connected by a cord with some recip- 
rocating part of the engine, or with the drum motion, so as 
to give it about 1% inches swing back and forth during 
each revolution of the shaft. The counter is provided with 
a convenient starting and stopping device, so that it can 
be made to begin or stop counting at any instant. 



78 HAWKINS' INDICATOR CATECHISM. 



. 



EXAMPLES OF DIAGRAMS. 



If an engine is in good condition, so that there is no 
leakage in the valves or piston, and everything well ad- 
justed, it should give a good card, without regard to its age. 

The diagram Fig. 56 has been obtained from a George 
H. Corliss and Nightingale engine, designed and patented 
in 1851, It is. a walking beam engine 23 in. x 60 in. 44 
revolutions, and was erected in 1852 — making it now 45 
years old, since which time it has been in constant use. 




Fig. 56. 

There has been one new cylinder, and the one now in use 
has been rebored three times. The engine is running to-day 
in Providence, R. L, and is quite a curiosity to professional 
men. 

The diagram Fig. 57 was taken from a Buckeye engine, 
and is shown as a sample diagram. As will be seen, the 
compression line runs into the admission line, without any 
mark, almost forming one line with it. The point of ad- 
mission is at A, at B the piston commences on its outward 
stroke, at C steam is cut off, at D is the point of release, 
and at F the point of compression. The line G y G is the 



HAWKINS' INDICATOR CATECHISM. 



79 



EXAMPLES OF DIAGRAMS. 

atmospheric line, H, H the line of a perfect vacuum, and 
/, / the clearance line. If the load varies while taking a 
card, the expansion and release lines will vary for different 




Fig. 57- 



revolutions, as is shown in Fig. 58, which is taken from a 
Buckeye engine, while the load changes from overload to 
a very light load, ranging the cut-off from \ stroke to \ 
stroke. 




Fig. 58. 



80 HAWKINS' INDICATOR CATECHISM. 






EXAMPLES OF DIAGRAMS. 

As an example of a very bad card, Fig. 59 is given. In 
it the admission is late, the steam line wire drawn, the cut- 
off slow at about y$ stroke ; the piston is leaking very 
badly, as is indicated by the sudden dropping of the expan- 
sion line ; the release is late beyond the center, causing a 
loop, which is due to the compression of the steam in the 
cylinder, until the exhaust valve opens ; and there is some 
back pressure, no compression. 

On single valve automatic engines the compression varies 
with the load, as well as the cut-off ; and, if the engine is 
lightly loaded, there is often a loop formed by excessive 
compression, as explained in Fig. 51 at b. 




Fig. 59. 

The card of a locomotive, when starting its load, is 
almost rectangular, as steam is admitted almost full stroke ; 
but after the train is up to speed, the engineer begins to 
" link up," cutting off earlier. 

But the compression is also then greater, and the 
admission earlier, and the card has the appearance shown in 
Fig. 60. 

The card shown in Fig. 61 was taken off a Hewes & 
Phillips Corliss engine, running non-condensing and with- 
out any back pressure, with cylinder diameter 16 inches, 



HAWKINS' INDICATOR CATECHISM. 



81 



EXAMPLES OF DIAGRAMS. 

stroke 38 inches, number of revolutions 75 per minute ; the 
boiler pressure, at the time the card was taken, was 56 
pounds by gauge. 




Fig. 60. 



Attention is called to the straight steam line, carried out 
to the point of cut-off ; the sharp cut-off, as well as the 
perfectly shaped compression line, running smoothly into 
the admission line. 




Fig. 6r. 

An engine which produces a card like Fig. 61 may be 
considered perfect both in adjustment and in design, 



82 



HAWKINS' INDICATOR CATECHISM, 



EXAMPLES OF DIAGRAMS. 

The cards shown in Figs. 62 and 63 were taken off a 
Watts-Campbell tandem compound Corliss engine ; Fig. 62 
being taken from the high pressure cylinder, while Fig. 63 
is the low pressure card. 




Fig. £2. 




Fig. 63. 

These cards show not only a very economical expansion, 
but also a very accurate action of both high pressure and 
low pressure valve gear. There is no drop in the steam 
lines of the high pressure cards — a fact which shows that 
there is ample port opening. 

The low-pressure steam lines will always drop, as the 
receiver pressure is reduced, as soon as the low-pressure 



HAWKINS' INDICATOR CATECHISM. 



83 



EXAMPLES OF DIAGRAMS. 

piston advances. The low-pressure card is taken with a 
spring of lower tension than the high pressure ; the card 
being thus larger, and consequently giving a better idea of 
the valve action. 

In Fig. 64 is shown a card taken of a Porter Allen 
engine, at very light load, as will be seen by the short cut- 
off. The boiler pressure was 74 pounds and the number 
of revolutions 286. There is considerable compression, 
but this is necessary at such a rate of speed. 




Fig. 64. 

The back pressure is only very slight, and the card may 
be looked upon as a fair specimen, and would undoubtedly 
have been very good if there had been more load upon 
the engine. 

Fig. 65 is a card of a 10x9 "Junior" Westinghouse 
engine at 350 revolutions per minute, and 80 pounds boiler 
pressure. 



84 HAWKINS' INDICATOR CATECHISM. 

EXAMPLES OF DIAGRAMS. 

The steam in this case is cut off beyond y$ stroke, caus- 
ing an insufficient expansion ; and besides, the maximum 
economy is not obtained ; otherwise, this card shows good 
valve adjustment. 

In indicating railroad locomotives, a great deal of atten- 
tion should be paid to the reducing motion, as the jarring 
of the engine would greatly interfere with the correctness 
of the diagram. 




Fig. 65. 

The reducing motion generally employed is a lever, 
which is made very solid, and well secured to the cross- 
head, and at its stationary point. 

The indicator likewise has to be fastened more than 
is practiced on stationary engines, as the fastening it 
receives by its cylinder coupling would not be sufficient, 
and it would be almost impossible to keep the pencil upon 
the paper. 



HAWKINS' INDICATOR CATECHISM. 



85 



EXAMPLES OF DIAGRAMS. 

The operator is protected from the wind and possible 
missiles by a sheet-iron box, surrounding the front of the 
boiler and both cylinders. 

The advantage of indicating railroad locomotives is illus- 
trated in cards Figs. 66, 67, 68 and 69. Fig. 66 was taken 




Fig. 66. 




Fig. 67. 



of a locomotive after the valves were set by the engineer, 
judging by the sound of the exhaust. 

The speed at which the engine was running when the 
card was taken was 208 revolutions per minute, with the 
lever at first notch. 



86 



HAWKINS' INDICATOR CATECHISM. 



EXAMPLES OF DIAGRAMS. 

Fig. 67 is the improvement on this card, after the valves 
were adjusted by the indicator. 




Fig. 68. 



Card Figs. 68 and 69 were also taken respectively before 
and after adjustment by the indicator, with the lever at 
third notch, at a speed of 210 revolutions per minute. 




Fig. 69. 



HAWKINS' INDICATOR CATECHISM. 



87 



INDICATING AIR COMPRESSORS. 



The use of the indicator is not entirely confined to the 
steam engine, although it was invented for this purpose by 
Watt. 

It may be used on compressed air engines, with the same 
result as on a steam engine, just as any steam engine could 
be operated by compressed air. 

The diagram would, in this case, have the same appear- 
ance as a steam engine diagram, and would record any 
defects in the valve adjustment in the same manner. 

The mean effective pressure can be found in the same 
way as explained for steam engine diagrams, and the horse 
power figured from the obtained results. 




Fig. 70. 

As compressed air engines are generally operated by 
much higher pressure than steam engines, the ordinary 
indicator springs will not answer for this purpose, and 
special springs have to be used. The indicator can also be 
used on the compressing cylinders of air and ammonia 
compressors. 



88 HAWKINS' INDICATOR CATECHISM. 

INDICATING AIR COMPRESSORS. 

The diagram obtained will differ from a steam engine 
diagram by being traced in the opposite direction, as 
shown in Fig. 70. 

The process of the operation is as follows: At A the 
suction valve closes, and the compression piston starts on 
its working stroke, and the air or ammonia vapor contained 
in the cylinder is compressed during this stroke, this may 
be called the compression line. 

At B the discharge valve opens, and the air escapes into 
the reservoir as fast as it is compressed by the piston ; thus 
the pressure is uniform, providing the pressure does not 
rise in the reservoir. 

At C, which is the end of the working stroke, the dis- 
charge valve closes, and the piston starts on its return 
stroke. 

The air remaining in the clearance space of the cylinder 
now expands, and the pencil drops, marking the expansion 
line until the pressure is equal to the atmospheric pressure, 
or properly a little below it, and the admission valve opens 
at Z>, and remains open during suction. 

In practice, however, the diagrams vary considerably 
from the one given as an example, as the operation of the 
valves will influence the lines to a considerable extent. 

The indicating of air or ammonia compressors in every- 
day practice is of no commercial value, and is only prac- 
ticed in experimental and erecting shops of the manufac- 
turer. 

The leakage of valves on an air or ammonia compressor 
is more readily ascertained by trial than by an indicator 
test. 



HAWKINS' INDICATOR CATECHISM. 89 



THE TABOR INDICATOR. 

The special peculiarity of the Tabor Indicator lies in the 
means employed to communicate a straight-line movement 
to the pencil, as shown in the appended cuts. 

A stationary plate containing a curved slot is firmly 
secured in an upright position to the cover of the steam 




Fig. 71. Tabor Indicator. 

cylinder. This slot serves as a guide and controls the mo- 
tion of the pencil bar. The side of the pencil bar carries a 
roller which turns on a pin, and this is fitted so as to roll 
freely from end to end of the slot with little lost motion. 
The curve of the slot is so adjusted, and the pin attached to 
such a point, that the end of the pencil bar which carries 



90 HAWKINS' INDICATOR CATECHISM. 

THE TABOR INDICATOR. 

the pencil moves up and down in a straight line, when the 
roller is moved from one end of the slot to the other. The 
curve of the slot just compensates the tendency of the pen- 
cil point to move in a circular arc, and a straight-line 
motion results. The outside of the curve is nearly a true 
circle, with a radius of one inch. 

The steam cylinder and the base of the paper drum are 
made in one casting. Inside the steam cylinder is a mova- 
ble lining cylinder, within which the piston of the indicator 
works. This cylinder is attached by means of a screw 
thread at the bottom, and openings on opposite sides at the 
top are provided for the introduction of a tool for screwing 
it in or out. Openings through the sides of the outer 
cylinder are provided to allow the steam which leaks by the 
piston to escape. 

The pencil mechanism is carried by the cover of the 
outside cylinder. The cover proper is stationary; but a 
nicely fitted swivel plate, which extends over nearly the 
whole of the cover, is provided, and to this plate the direct 
attachment of the pencil mechanism is made. By means of 
the swivel plate, the pencil mechanism may be turned so as 
to bring the pencil into contact with the paper drum, as is 
done in the act of taking a diagram. 

The pencil mechanism is attached to the swivel by means 
of the vertical plate containing the sloe, which has been 
referred to, and a small standard placed on the opposite 
side of the swivel for connecting the back link. The 
slotted plate is backed by another plate oi similar size, 
which serves to receive the pressure brought to bear on the 
pencil bar when taking diagrams, and also to keep it in 
place. 



HAWKINS' INDICATOR CATECHISM. 91 

THE TABOR INDICATOR. 

The connection between the piston and the pencil 
mechanism is made by means of a steel pitman. At the 
upper end, where it passes through the cover, it is hollow, 
and has an outside diameter measuring T 3 ^- of an inch. At 
the lower end it is solid and its diameter is reduced. It 
connects with the piston through a ball and socket joint. 
The socket forms an independent piece, which fits into a 
square hole in the center of the piston, and is fastened by 
means of a central stem provided with a screw, which 
passes through the hole and receives a nut applied from the 
under side. This nut has a flat-sided head, so as to be 
readily operated with the fingers. A number of shallow 
grooves are cut upon the outside of the piston, which 
serve as a water packing. 

The springs used in the Tabor Indicator are of the du- 
plex type, being made of two spiral coils of wire with fit- 
tings. These springs are so mounted that the points of 
connection of the two coils lie on opposite sides of the 
fitting. The drum spring, by which the backward move- 
ment of the drum is accomplished, consists of a flat spiral 
spring of the watch-spring type, placed in a cavity under 
the drum carriage encircling the bearing. It is attached at 
one end to the frame below, and at the other end to the 
drum carriage. In its normal position the drum carriage 
is kept against a stop by means of the pull of the spring. 
By loosening a thumb-screw which encircles the shaft and 
holds the drum carriage down to place, the carriage may be 
lifted so as to clear the stop, and the tension on the spring 
may then be adjusted. This is done by simply winding or 
unwinding, as desired. 



92 HAWKINS' INDICATOR CATECHISM, 

THE TABOR INDICATOR. 

A simple form of carrier pulley serves to operate the 
driving cord from any direction. A single pulley is 
mounted within a circular perpendicular plate, the center 
of which coincides with the center of the driving cord. 
This center also coincides with the circumference of the 
pulley. The plate can be turned about its center so as to 
swing the pulley into any desired angular position, and 
thereby lead the cord off in any desired direction. The 
plate is held by a circular frame, which serves also as a 
clamp, and the pulley is fixed in position by the use of the 
same nut that secures the frame to the pulley arm. 






HAWKINS' INDICATOR CATECHISM. 93 



THE BACHELDER ADJUSTABLE SPRING 
INDICATOR. 

The Bachelder adjustable spring indicator is shown in 
Figs. 72 and 73 — Fig. 73 being a longitudinal section 
through the instrument. 

In Fig. 72 a nerled cap is removed on the side of the 
instrument, through which the interior of the cylinder can 
be seen, also the connection of the spring and piston rod. 

The special features of this instrument consist in the 
T-shaped hollow case, adjustable flat spring, and positive 
parallel motion. The cylinder, being separate from the case 
proper, is screwed to the lower end, where it is held by a 
small set screw. By turning this screw one-half of a turn 
the cylinder can be unscrewed ; then, to remove the piston, 
take out the screw at the end of the spring, and at the con- 
nection with pencil lever. These are the only parts neces- 
sary to remove for cleaning. The flat steel spring works 
in the horizontal body of the case, one end being rigidly 
secured by means of a taper steel screw, and the other 
attached to the connecting rod between the piston and 
pencil lever. The change of spring is made by removing 
the screw that connects it to the piston rod, and the one 
that holds it in the case. The range of the high-pressure 
spring is so great that a change is only necessary when 
using on a compound or triple expansion engine. Connec- 
tion is made to the piston with a ball and socket joint. 
Access can be had to the piston for oiling or removing, by 
unscrewing nerled cap on face of instrument, 



94 HA W KINS' INDICA TOR CA TECHISM. 



THE BACHELDER ADJUSTABLE SPRING INDICATOR. 




Fig. 72. Bachei,der Indicator. 




Fig. 73. Longitudinal Section through Bache^der Indicator. 



HAWKINS' INDICATOR CATECHISM. 



95 



THE BACHElyDER ADJUSTABLE SPRING INDICATOR. 

A split bushing in the case is provided with 
a longitudinal recess for the reception of the 
spring. In the upper side of the bushing a 
hardened steel pin is inserted. The lower side 
of the case has a longitudinal slot, through 
which a set screw passes, and through the lower 
side of the bushing, directly opposite the steel 
pin, so that when the screw is tightened, the 
spring is held rigidly between it and the steel 
pin. To change from one scale to another, 
loosen the set screw and slide the bushing along 
until the mark on projecting block is opposite 
the scale required ; then tighten the screw. The 
scales are marked on the face of the case, the 
upper one being for high pressure, and the 
other for low pressure. The parallel motion is 
secured by confining the end of the pencil lever 
in a small roller which runs in the vertical slot. 
The height of atmospheric line is adjustable by 
means of a swivel in connecting rod near the 
pencil lever. 

The flat spring used in this instrument is 
shown in full size in Fig. 74. 



Fig- 74. 



96 



HAWKINS' INDICATOR CATECHISM. 



THE IMPROVED THOMPSON 
INDICATOR. 

Figs. 75 and 76 represent the Improved Thompson Indi- 
cator, manufactured by Schaeffer & Budenberg, New York 
and Chicago. 




Fig. 75- Improved Thompson Indicator. 



Fig. 76 shows a sectional view of this instrument in its 
present improved form, the following being a description of 

the cut. 



HAWKINS' INDICATOR CATECHISM, 



97 



THE IMPROVED THOMPSON INDICATOR. 

The swivel bar B is connected to the piston rod by a 
short pitman /^with a ball joint R at its lower end. 

The diameter of piston of the standard size instrument is 
0.798 inch = ]/ 2 inch area. 




Vig. 76. Improved Thompson Indicator. (Sectional View.) 



The lead pulley V is carried by the swivel W, and can be 
locked in any position by the small set screw. The swivel 
plate Fcan be swung in any direction in its plane and held 



98 HAWKINS' INDICATOR CATECHISM. 



THE IMPROVED THOMPSON INDICATOR. 

firmly by the thumb-screw Z. Thus with this combination, 
the cord can be run in any desired direction, and cannot 
ride over, being led to the drum through the small passage 
in W. 

The link A, having long bearings, as can be seen in Fig. 
75, gives a very good support to the lever B. The base C, 
supporting the paper drum, and the main body D> are cast 
in one-piece. 

The paper drum is made with a closed top to preserve its 
accurate cylindrical form, and the top having a journal 
bearing at U in the center, compels a true movement to its 
surface. 




Fig. 77- 

The spring E and the spring case F are secured to the 
rod G by screwing the case Flo a shoulder on G, by means 
of a thumb-screw H. 

To adjust the tension of the drum spring, the drum can 
be easily removed, and by holding on to the spring case E 
and loosening screw H the tension can readily be varied 
and adapted to any speed, to follow precisely the motion of 
the engine piston. 

The bars of the nut / are made hollow, so as to insert a 
small short rod K y which is a great convenience in unscrew- 
ing the indicator when hot. 

The indicator is so constructed that it can be readily 
changed and adapted to high-pressure work. This is done 



HAWKINS' INDICATOR CATECHISM. 



99 



THE IMPROVED THOMPSON INDICATOR. 

by simply removing the cone M (see Fig. 76) and substitut- 
ing the cone iV(Fig. 77), with % square inch piston and its 
rod. 

Taking the 100-pound spring with the Yz square inch 
area piston, a pressure of 250 pounds can be correctly 
indicated. When pressures beyond this are required to be 
indicated, the % square inch piston is used, and with the 
100-pound spring, 500 pounds can be indicated. 




100 HAWKINS' INDICATOR CATECHISM. 




Fig. 78. The Lyne Indicator. 



HAWKINS' INDICATOR CATECHISM. 101 



THE LYNE INDICATOR. 

In Fig. 78 is shown another form of indicator, manufac- 
tured by Schaeffer & Budenberg. 

It differs from that previously described by the parallel 
motion, as will be seen in the cut. 

The interior construction of the paper drum is similar to 
the one attached to the Improved Thompson Indicator. 
It is also provided with the combination swivel for the 
guide pulley. 



THE BUFFALO INDICATOR. 




Fig. 79- 




Fig. 80. 



This instrument is shown in Fig. 79, and in Fig. 80 in 
section, exposing the interior parts. 



102 HAWKINS' INDICATOR CATECHISM. 

THE BUFFALO INDICATOR. 

The piston is one-half inch area, provided with water- 
grooves. The piston rod is made of T 3 T inch steel, hollow 
at the upper end, threaded to receive a swivel head (which 
permits of the adjustment of the pencil to suit weak or 
strong vacuum springs) and turned smaller at the lower to 
reduce its weight. 

The parallel motion is secured by a link attached to and 
governing the pencil lever direct. The screws of this link 
are made free from any appreciable loss motion, and will 
remain so indefinitely. It is made of tool steel, and will 
trace a correct vertical line within its limit of 3 inches. 
The arm, link and uprights are made of T S T x 3^ inch steel, 
the uprights being held together by small bars ^ inch 
diameter, \ inch long, the ends of which are turned smaller 
and threaded to receive the \ inch hex nuts, which fasten 
the uprights against the shoulder. 

The drum spring is a flat coil of the clock pattern, and 
can be adjusted for any speed by unscrewing the thumb- 
screw. 

The indicator spring is of the double-coil pattern. 




HAWKINS' INDICATOR CATECHISM. 



103 



THE CROSBY INDICATOR. 

The Crosby indicator is shown in Fig. 81, which is an 
outside view, and also in Fig. 82, which shows a sectional 
view. 

These illustrations show the design and arrangements of 
the parts of the Crosby steam engine indicator. 




Fig. 81. Crosby Indicator. 

Part 4 is the cylinder, in which the piston moves. 
Between 4 and 5 is an annular chamber, which serves as a 
steam jacket, and it is always filled with steam of nearly 
the same temperature as that in the cylinder. 



104 HAWKINS' INDICATOR CATECHISM. 



THE CROSBY INDICATOR. 

The piston, 8, is formed of tool steel. Its shell is made 
as thin as possible consistent with proper strength. Hollow 
channels in its outer surface provide a steam packing, and 
the moisture and oil which they retain act ns lubricants. 




Fig. 82. Crosby Indicator (Sectional View). 

The transverse web near its center supports a central 
socket, which projects both upward and downward ; the 
upper port is threaded inside to receive the lower end of 
the piston rod. 

The upper edge of this socket is formed to fit into a 
circular channel in the under side of the shoulder of the 



HAWKINS' INDICATOR CATECHISM. 105 

THE CROSBY INDICATOR. 

piston rod, when it is properly connected. It has a 
longitudinal slot, which permits the ball bearing on the end 
of the spring to drop to a concave bearing in the upper 
end of the piston screw 9, which is closely threaded into 
the lower part of the socket. 

The piston rod, 10, is of tool steel, and made hollow for 
lightness. 

When connecting the piston rod to the piston it should 
be screwed into the socket as far as it will go ; that is, until 
the upper edge of the socket is brought firmly against the 
bottom of the channel in the piston rod. 

The swivel head, 11, is threaded on its lower half to 
screw into the piston rod, more or less, according to the 
required height of the atmospheric line on the diagram. 

The cap, 2, screws into the top of the cylinder, and holds 
the sleeve and all connected parts in place. 

Its central hole is furnished with a hardened steel bush- 
ing, which forms a guide for the piston rod. 

The sleeve, 3, surrounds the upper part of the cylinder, 
and supports the pencil mechanism. 

The plate, 1, supports the paper drum, 24. 

The drum spring, 31, is a short spiral spring. 



106 HAWKINS' INDICATOR CATECHISM. 



MEASURING THE DIAGRAM BY 
ORDINATES. 

In order to figure the horse power of an engine, it is 
necessary to know the exact pressure upon the piston. 

This pressure can never be equal to the full boiler pres- 
sure, as even those engines known as full-stroke engines 
cut the steam supply off before the end of the stroke, and 
thus the same pressure does not follow the piston through- 
out the entire stroke. The pressure varies through the 




Fig. 83. 

stroke, and is opposed by a varying amount of back pres- 
sure, so that the average unbalanced, or, as it is commonly 
called, the " mean effective pressure," must be determined. 
There is also some pressure lost between the cylinder and 
boiler by wire drawing. 

The indicator diagram records the pressure at all points 
of the stroke, and thus allows, by a simple calculation, the 
finding of the mean effective pressure. 



HAWKINS' INDICATOR CATECHISM. 107 



MEASURING THE DIAGRAM BY ORDINATES. 

The mean effective pressure is the pressure which, if 
allowed to act upon the piston throughout the entire 
stroke, would do the same amount of work as the steam 
pressure, cut off and expanded down, as indicated by the 
diagram. 

It is the average pressure, arrived at by measuring the 
pressure in the cylinder at different points of the stroke 
next adding all these together, and then dividing by the 
number of points measured. 




Fig. 84 

In an indicator diagram, the height is proportional to the 
pressure, and to find the average pressure we must find the 
average height. 

The most elementary way of doing this is by measuring 
the pressure upon the diagram at a number of equidistant 
points and taking the average. To do this, divide the dia- 
gram into a number of equal parts lengthwise, ten for ordi- 
nary work, as shown by the dotted lines in Fig. 83. Now 
with a scale corresponding to the spring with which the 
diagram was taken, measure the pressure in the center of 



108 HAWKINS' INDICATOR CATECHISM. 



MEASURING THE DIAGRAM BY ORDINATES. 

each of these divisions ; that is, upon the full lines, or ordi- 
nates. Notice that this pressure must be measured be- 
tween the steam, expansion and exhaust lines of the dia- 
gram, whether the engine is condensing or non-condensing, 
and not from the atmospheric or any other line. 




Fig. 85. 




Fig. 86. 



HAWKINS' INDICATOR CATECHISM. 



109 



MEASURING THE DIAGRAM BY ORDINATES. 

Several expedients may be resorted to for shortening the 
labor of dividing the diagram and locating the ordinates. 
The simplest of these is to have a rule, a little longer than 
the ordinary length of diagrams, divided as shown in Fig. 
84, just as the diagram is to be divided, with nine spaces 
of equal length in the middle ; the two end spaces, o to 1 
and 10 to o, being one-half the width of the others. Four 
inches between the zero marks of the rule is a good length 
for diagrams from 3^ to 4 inches in length. 




Fig. 87. 

Draw the lines O A and X B at the extreme ends of the 
diagram and perpendicular to the atmospheric line. Place 
the rule between them, as shown in Fig. 84, at such an 
inclination that both zeros come upon the perpendiculars. 
Then with a needle-point prick the card opposite each divi- 
sion of the rule, and draw the ordinates perpendicular to 
the atmospheric line and through these points. Of course 
any other number of ordinates than 10 or 20 may be used. 



110 HAWKINS' INDICATOR CATECHISM. 

MEASURING THK DIAGRAM BY ORDINATES. 

There are devices on the market for simplifying this 
operation, and for doing it with more exactness. Two of 
these are shown in Figs. 85 and 86. 

The method of using them will be plainly understood 
from the cuts. 

Instead of measuring each ordinate with the scale cor- 
responding to the spring with which , the diagram was 
taken, some engineers prefer to lay off the lengths of the 
ordinates continuously on the edge of a strip of paper, 
then to measure the whole length with a scale of common 
inches, and multiply the length by the scale of the spring. 

The result will be the height of a rectangle, whose base 
is equal to the length of the diagram, and whose area 
equals the area of the diagram. 

If there is a negative loop in the diagram, as in Fig. 87, 
the cause of which has been explained, the average pres- 
sure of the loop portion of the diagram must be subtracted 
from that of the other portion. For the piston is actually 
hanging back upon the engine, and the loop not only rep- 
resents no addition to the useful mean effective pressure, 
but a force acting against the motion of the engine equiva- 
lent to so much back pressure. For example, erecting the 
ordinates as before directed, and measuring with a scale, 
in this case 40, we have 98 + 93 + 40 + 20+5 = 256 as the 
sum of the measurements in the main portion of the dia- 
gram, and 3 + 8+13 + 15 + 11 =50 as the sum of the meas- 
urements in the loop. Taking the difference and dividing 
by 10 to get the average, we have 

256 — 50 

— 20.6 lbs. M. E. P, 

10 






HAWKINS' INDICATOR CATECHISM. Ill 



EXAMPLES. 

In the following illustrations are given examples ex- 
plaining, at some length, how to measure diagrams by 
ordinates. 

Fig. 88 shows an ideal diagram, in which the pressure is 
indicated at different points of the stroke, and also showing 
the mean effective pressure. 

Figs. 89 and 90 are diagrams of a tandem compound 
Watts-Campbell Corliss engine, in which the method for 
finding the mean effective pressure of a double diagram is 
given. 

The diagrams in Figs. 91, 92, 93 and 94 are of a cross 
compound Buckeye engine, taken at the same instant, with 
four indicators ; thus the cards are all separate, but the M. 
E. P. of both strokes can be found by proceeding as in 
Figs. 89 and 90. 

The following diagrams were taken of the engines named 
above, and are used to more fully explain to the student 
the working out of an indicator diagram by ordinates. 

By repeating this operation several times, the student 
will get so accustomed to it that he can •almost tell the 
mean effective pressure by looking at the diagram and 
knowing the boiler pressure. 

If the foregoing explanations and rules are well observed, 
the art of figuring diagrams will be found to be quite easy. 



NOTE. — In the following diagrams H. P. stands for High Pressure ; 
I. P. for Intermediate Pressure ; and L,. P. for I^ow Pressure. Letters 
C and H represent Crank End and Head End, as heretofore explained, 
M. E- P. is an abreviation for Mean Effective Pressure, 



112 HAWKINS' INDICATOR CATECHISM, 



EXAMPLES. 




Fig. 88. 



io)34775 =34775" 

M. E. P. 



HAWKINS' INDICATOR CATECHISM. 113 



EXAMPLES. 




10)351.30=35.13= Fig- 89. 

M. E. P. 



10)351.70=35.17 = 
M. E. P. 



M. E. P. of both strokes = 



35-17 
35-13 



2)70.30 = 35.15. 



114 HAWKINS' INDICATOR CATECHISM. 



EXAMPLES. 



3-34 
4-3 

5-5 
6. 7 
8.23 

io 

13-5 
15-3 
16.25 

17-5 



10)100.62 = 10.062 = 

M. E. P. 




Fig- 90. 1 0)96. 1 8 — 9.6 1 8 = 

M. E. P. 



M. E. P. of both strokes = 



10.062 
9.618 



2)19.680 = 9.84 



HA I VK INS' INDICATOR CATECHISM. 115 



EXAMPLES. 



I03-75 




Fig. 91. 10)588.85 =58.885 : 

M. E. P. 



116 HAWKINS' INDICATOR CATECHISM. 



EXAMPLES. 



102.25 




Fig. 9 2 - 10)601.75=60.175= 

M. E. P. 



HAWKINS' INDICATOR CATECHISM. 117 



EXAMPLES. 




10)113.55 — u-355- 

M. E. P. 
Fig- 93- 



118 HAWKINS' INDICATOR CATECHISM. 



EXAMPLES. 







Fig. 94. 



10)107.24=10724 



HAWKINS' INDICATOR CATECHISM. 



119 



EXAMPLES. 

Instead of finding the mean effective pressure for each 
end of the cylinder, and then taking the average, the sums 
of each end may be added together, and the result divided 
by 20, as in Figs. 95, 96 and 97, which are cards from a 
triple expansion Buckeye engine. 



9 


\ 


— ~^~^/U 


69.5 


17 




. __-J - 




68 


27 




- — — 4- — 




68 


35-25 




—/— 


1 


67 


52 


Pi y/ 




61.25 


62 


H 


ix — — ~~ 


■ — 


5o 


63.25 


- — \- 




32 


63.25 


V — 


1— 


25-5 


64 








16 










61.5 


) 


j._____^ 




8 



454.25 



Fig- 95- 



465.25 



465.25 
454.26 



20)919.50=45.975-=*!. E. P. 



120 JTAWK /US' IN DfC 'A TOR CATECHISM. 



EXAMPLES. 




151.70 



Fig. 96. 



162.OO 



162.OO 
151.70 

20)31 3.70-=! $.68s=-M. E. P. 



HAWKINS' INDICATOR CATECHISM. \i\ 



EXAMPLES. 




99- 30 



Fig. 97. 



102.22 



102.22 
99-30 



20)201.52=10.076— M. E. P. 



!>•> //.ill' KINS' INDICATOR CATECHISM. 



PLANIMETER. 

The foregoing method of figuring the mean effective 
pressure is sufficiently accurate for ordinary purposes; but, 
if very exact results are required, an instrument is used 
which enables the operator to find the mean effective pres- 
sure with still greater accuracy. This instrument is called 
the Planimeter. 

By its use the area of the diagram is measured, and by 
simply dividing this area by the length of the diagram, the 
average height is found. If the area of a rectangle and its 
length are given, the height can easily be found by divid- 
ing the area by the given length. 

Now, if the area of an indicator diagram is given, and 
divided by its length, the result will be the height of a 
rectangle, of equal area and length with the diagram. 

This would be the kind of figure marked upon the paper 
by the indicator pencil, if a pressure equal to the mean 
average should act upon the piston throughout the entire 
stroke. 

The planimeter is made in a variety of forms. The 
Amsler was the first to be introduced, a typical example 
of which is shown in Fig. 98. It consists of two arms 
pivoted together at the top, upon one of which is carried a 
roller free to revolve upon an axis parallel to the arm itself. 
The roller is divided circumferentially into ten equal parts, 
each of which represents a square inch of area, and each of 
these parts is further divided into equal parts representing 
each one-tenth of a square inch, as shown in Fig. 99. 
Close to the edge of the roller is a stationary plate having 



HAWKINS' INDICATOR CATECHISM. 



123 



THE PLANIMBTER. 

the same curvature and containing a vernier made by divid- 
ing a space nine-tenths as long as one of the large divisions 
of the roller into ten equal parts. In Fig. ioo let the space 
between A and B represent one of the larger divisions of 
the wheel, and the space between C and D the vernier. 

In reading the instrument take the number on the 
wheel that has passed the zero mark of the vernier when 
the wheel is turning to the left as indicated by the arrow, 





Fig. 98. 



Fig. 99. 



as the number of whole square inches, in this case 6. The 
tenths of a square inch are indicated by the number of 
spaces, such as a y which have passed the zero mark, in this 
case 1; so that the reading of the scale as laid down in Fig. 
100 is 6.1 square inches. Now notice that the space be- 
tween the line b and the line 1 on the vernier is just one- 
tenth of one of the spaces such as a upon the roller, the 



124 HAWKINS' INDICATOR CATECHISM. 

THE PIvANIMBTKR. 

space between the lines 2 and c is just two-tenths, between 
3 and d three-tenths, etc. If, then, the wheel rolls in the 
direction of the arrow one-tenth of one of the spaces a, 
corresponding to an area of one one-hundredth of a square 
inch, the lines I and b will coincide, for two one-hundredths 
2 and c would coincide, so that we get the hundredths of 
a square inch by writing that number on the vernier which 
is opposite any line on the wheel. For instance, in reading 
the instrument as it stands in Fig. 99, write first the num- 




Fig. 100. 

ber on the wheel to the left of the zero mark, in this case 
4; then the number of whole spaces between that number 
and the zero mark, in this case 7 ; and last the number on 
the vernier which is in line with a mark on the wheel, in 
this case 3. The whole reading therefore is 4.73 square 
inches, the decimal point being placed after the 4, the 7 
and 3 being tenths and hundredths as before explained. 
It will be noticed that only the zero, 5, and 10, are num- 
bered on the vernier in Fig. 99, and this is the case in the 
actual instrument, the intermediate marks being easily 
known by their position. The eye soon becomes accus- 



HAWKINS: INDICATOR CATECHISM. 125 



THE PLANIMETER. 




Fig. 101. 




Fig. 102, 



126 HAWKINS' INDICATOR CATECHISM. 



THE PlyANIMETBR. 

tomed to quickly determining the mark upon the vernier 
which coincides with one upon the wheel, the marks at 
either side of it being just within the marks upon the 
wheel, giving the arrangement shown at A in Fig. 99. 

The planimeter should be used upon a smooth but not 
slippery surface, such as that of heavy drawing-paper or 
Bristol board. Place a sheet of this large enough to in- 
clude the planimeter and the diagram upon the drawing- 




Fig. 103. 

board, which is furnished with many planimeters made of 
hard wood polished and fasten it with thumb-tacks or 
paper-clips, which resemble those on the paper drum of an 
indicator, and are fastened to the board furnished with the 
planimeter. Set the stationary point of the planimeter 
into the paper in such a position that the tracing-point can 
be carried around the outline of the diagram without bring- 
ing the wheel in contact with the card. The instrument 
can be worked to the best advantage when it is neither 



HAWKINS' INDICATOR CATECHISM, 127 

THE PLANIMETER. 

allowed to close up too closely, as in Fig. 101, nor to extend 
too widely, as in Fig. 102. A better position for the sta- 
tionary point than either of these is shown in Fig. 103, the 
motion of the roller being easiest when the arms are near 
a rectangular position. Where the areas to be measured 
are large, or where there is considerable space between the 
top of the diagram and the top edge of the card, contact 
of the roller with the edge of the card may be avoided by 
inverting the diagram, as indicated by the dotted diagram 




Fig. 104. 

in Fig. 103, using the planimeter always in the same direc- 
tion — that in which the hands of a watch run ; for obviously 
the area of the diagram remains the same in whatever posi- 
tion the card is placed. 

Place the tracing-point on any convenient point in the 
line of the diagram, and by pressing upon it get a slight in- 
dentation to mark the point of starting. Take the reading of 
the instrument as it stands ; then with the tracing-point 
follow the line of the diagram in the direction in which the 
hands of a watch move, as indicated by the arrows in Figs. 
104 and 87. Follow the line as made by the pencil ; not 



/ 

128 HAWKINS' INDICATOR CATECHISM, 

THE PLANIMETKR. 

necessarily in direction, but rather in course — as, on a 
right handed diagram, such as Fig. 104, it will have to be 
traced in the opposite direction from that of the pencil 
which made it, in order to carry the tracing-point in the 
direction of the hands of a watch. 

For instance, in Fig. 105, do not leave the admission line 
at a and run out on the back pressure line, but follow the 
diagram naturally all the way around, as the arrows indi- 
cate, and as it was drawn by the pencil. 




Fig. 105. 

If the pointer traces in the opposite direction to the 
hands of a watch, the wheel will take out the area instead 
of adding it. In Fig. 87 it was shown that the area of the 
loop was negative, and that it needed to be subtracted from 
the other portion of the diagram to get the mean effective 
pressure. It will be seen that, by following the lines of the 
diagram as directed, the point will pass around the negative 
portions of the diagram in a direction contrary to that of 
the hands of a watch, and that these, areas will be auto- 
matically subtracted. In this connection, be careful in 



HAWKINS' INDICATOR CATECHISM 129 

THE PLANIMETER. 

starting to trace a diagram with loops, to move the tracing- 
point in the direction that will carry it with the hands of a 
watch over the main portion of the diagram. If Fig. 105, 
for instance, were started at the point a> or anywhere 
within one of the loops, the first movement of the tracer 
would have to be in the opposite direction from that of 
the watch. 



130 HAWK I ISIS' INDICATOR CATECHISM. 

FINDING THE MEAN EFFECTIVE PRESSURE 
BY THE PLANIMETER. 

Having traced around the diagram and brought the 
pointer around and into the hole from which it started, 
take the reading in the new position, subtract from it the 
previous reading, and the difference will be the area of the 
figure traced. If the roller is placed at zero to start with, 
the reading would give the area at once ; but it is easier to 
take the instrument as it stands and subtract the initial 
reading. Suppose the operation is started with the wheel 
at 1.42, and after tracing the diagram the reading is found 
to be 4.69, then the area will be 4.69 — 1.42 = 3.27 square 
inches. 




Fig. 106. 

By dividing this area by the extreme length the average 
height is found. 

The length of the diagram has to be measured between 
its extremes— i. e. y between b and d, Fig. 106. 

If both diagrams are taken on one card, do not measure 
between the extremes of both diagrams at once, as indi- 
cated in Fig. 106, but measure each diagram by itself, as 
marked right length, Fig. 106. 






HAWKINS' INDICATOR CATECHISM. 131 



THE LIPPINCOTT PLANIMETER. 

In Figs. 107 and 109 are shown two other types of plani- 
meters ; the standard averaging planimeter, Fig. 109, is of 
the " Amsler " type, which has been described in the pre- 
ceding pages. This can be used to measure the mean 
effective pressure directly, or to find the area of the dia- 
gram as previously stated. 

Fig. 107 represents the Lippincott planimeter, which en- 
tirely does away with calculations. Its principal parts are 
a polar arm of constant length, R C y a tracing arm of vari- 
able length, C T, and a registering arm which carries a 
wheel. This arm is of glass in the form of a tube which is 
exhausted for partial vacuum, and in its interior is a paper 
scale which is thereby protected from discoloration and 
shrinkage from varying atmospheric conditions. The wheel 
has a sharp knife edge, and therefore does not skid laterally, 
as do the wheels of all other planimeters or integrators, all 
lateral motion being performed by the sliding of the wheel 
upon the tube. Thus it will be seen that a finished surface 
is not necessary with this instrument ; it will be further 
noted that simple rotation of the wheel upon its axis does 
not register on the scale arm, therefore the diameter of the 
wheel is immaterial. 

The wheel and tube are shown in Fig. 108. 

At C it will be noted that there is a little button which 
may be depressed and push a sharp point through the 
exact center of the pivot of the tracing and polar-arm and 
thereby exactly locate it. Thus the tracing-arm can be 
adjusted to any length with accuracy. One or more tubes 



132 HAWKINS' INDICATOR CATECHISM. 



PLANIMETKRS. 




Fig. 107. The Lippincott Pi,animeter. 




Fig. 108. Scai<e and Wheei,. 




Fig. 109. The Robertson-Amsi,er Pi^animeter. 



Note. — Both these instruments are manufactured by J. L Robert- 
son & Sons, 204 Fulton Street. N. Y. 



HAWKINS' INDICATOR CATECHISM, 133 



PLANIMETER ATTACHMENT. 

are supplied with a planimeter, each corresponding with 
two scales of indicator spring. By adjusting the tracing- 
arm to the exact length of the card, clamping it in this 
position and selecting a tube of the proper scale, the indi- 
cation thereon when the card is traced will be not the area, 
but the mean effective pressure. 

If it be desired to find the area of the diagram, all that 
is necessary to do is to set the tracing-arm four inches, 
and select a tube with a 40 scale. The results will then be 
areas instead of mean effective pressures, and it will be 
seen that the length of the card and the scale of the spring 
cancel each other. 




Fig. no. 

In Fig. no is shown in detail the recording mechanism 
attached to the Amsler planimeter by the Crosby Steam 
Gauge and Valve Company. 

The drum of the roller-wheel D is divided into ten num- 
bered parts, and each number represents one square inch ; 
the spaces between the numbers are divided into ten grad- 
uations, each one of which represents one-tenth of a square 
inch. The vernier E has ten graduations, one-tenth less 



134 HAWKINS' INDICATOR CATECHISM 

PLANIMETER ATTACHMENT. 

than those of the roller-wheel, and if one of them exactly 
coincides with a graduation on the roller-wheel, it repre- 
sents — counted from zero — so many hundredths of a square 
inch. 

The counting-disc G is geared to the wheel in such a 
manner as to rotate once for 10 rotations of the roller- 
wheel ; it is divided into 10 numbered spaces, each one of 
which represents 10 square inches; its office is to count the 
revolutions of the roller-wheel. 

Referring now to Fig. no, and supposing that a certain 
area has been measured, from zero, the result is read as 
follows : Suppose the figure on the counting-disc which has 
passed the line on the posty is found to be I, representing 
tens, and the figure on the roller-wheel which has passed 
zero on the vernier to be 4, representing units ; and the 
number of intermediate graduations on the roller-wheel 
that have also passed zero on the vernier to be 7 (shown by 
the dotted line a), representing tenths ; and the graduation 
on the vernier, which exactly coincides with a graduation 
on the roller-wheel to be the third from zero, which for 
instance call 3 and represents hundredths ; then 14.73 
square inches is the area of the figure measured. 

If the movement of the roller-wheel had been three one- 
hundredths less, its seventh graduation would have coin- 
cided with zero of the vernier and there would have been 
no hundredths to read. The reading would then have been 
14.7 instead of 14.73. 



HA WKINS' 1NDICA TOR CA TECH ISM. 135 



THE WILLIS PLANIMETER. 



The Willis planimeter, which is shown in Fig. in, reads 
the horse power direct from the indicator card. 




i36 HAWKINS' INDICATOR CATECHISM. 



THE WILUS PIvANIMETER. 

Its wheel both rolls and slides on its axis, which is per- 
pendicular to the tracer bar A B. It rolls for all move- 
ments paralled to the tracer bar, and slides on its axis for 

all movements perpendicular to it. 

After tracing a figure, the result of 

such perpendicular movement is read 

from the scale next the wheel, Fig. 

ill. This scale is triangular, and 

any one of its six graduated edges 

can be brought next the wheel. Thus 

the wheel movement can be read in 

^ the unit best suited to the work, and 

all factors or corrections are avoided. 

To read square inches, set the 

w « points A and B to the distance apart 

M 

corresponding to the scale that is 
next the wheel. Thus, if the 40 
scale were next the wheel, set A and 
B 4 inches apart. The instrument 
would then read square inches and 
tenths of a square inch ; for the read- 
ing, after tracing a figure whose area 
was one square inch would be 

4.oX^= 1.0. 

If the figure is large and the con- 
venience of a longer tracer arm is 
desirable, turn next to the wheel the 
100 scale, and set A and B 10 inches 
apart, and still read the same unit. 
To read the mean effective pressure of an indicator card, 
turn next to the wheel the scale that corresponds to the 






HAWKINS' INDICATOR CATECHISM. 137 



THE WILLIS PLANIMKTER. 

spring with which the card is taken, and set points A and 
B to card length, Fig. 112. On tracing-card the reading 

card area . .. r ^ 

— X-l n: X spnng =M. E. P. 

card length 

The horse-power attachment, Fig. 1 13, is a double-hinged 

scale, with a sliding pointer on each arm. Supplied with 




138 HAWKINS' INDICATOR CATECHISM. 



THE WILIylS PIvANIMKTER. 

the instrument is a book of tables which give the value of 
33,000 



piston area X stroke 



for engines from %"■*&" to iio // x72 // . 







As these tables run by half-inch differences in diameters, 
and inch differences in strokes, they may be said to give 



HA WKINS' IN DIC A TOR CA TECH ISM. 139 

THE WILLIS PLANIMETER. 

this value for any engine. To read horse power, the lines 
p and q> Fig. 113, are set to the division corresponding to 
the revolutions per minute of the engine, and the points G 
and H are set to card length, Fig. 114. The scale that 
corresponds to the spring with which the card is taken is 
turned next to the wheel, and points A and B are set to 

the division corresponding to the value — : — — — 

piston area X stroke 

as given by the tables. The attachment is removed, and 

the card traced. The reading will be horse pow r er. 

If both diagrams are taken upon the same card, start the 
tracer point at the intersection of the two expansion 
curves, and tracing first one and then the other read the 
total horse power direct from the scale. Thus the instru- 
ment performs automatically all the operations called for 
by the usual formula for horse power, and does it without 
sacrificing accuracy, simplicity or portability. 

The wheel is mounted upon a glass rod, and needs no 
lubrication. The scale is of box wood, finely graduated, 
and the rest of the instrument is of brass (nickle plated) 
and steel. It is supplied by its inventor, E. J. Willis, M. E., 
211 East Franklin Street, Richmond, Va. 



140 HAWKINS' INDICATOR CATECHISM. 



THE COFFIN AVERAGING 
PLANIMETER. 

The Coffin Averaging Planimeter is illustrated in Fig. 
115. The construction of it is plainly shown. 




Fig. 115. Coffin Planimeter 

In using the Coffin averager, the grooved metal plate /is 
first connected to the board upon which the apparatus is 
mounted, in the position shown in the cut, being held in 



HAWKINS' INDICATOR CATECHISM. 141 



THE COFFIN AVERAGING PLANIMETER. 
place by a thumbscrew applied from the back side. The 
indicator card is then placed under the clamps C and K, 
which may be sprung away from the board a sufficient 
amount to allow the card to be introduced, and the card is 
moved toward the left into such a position that the atmos- 
pheric line is near to and parallel with the lower edge of 
the stationary clamp C, while the extreme left-hand end of 
the diagram is even with the perpendicular edge of the 
clamp. The movable clamp K, which is fastened at the 
bottom to a sliding plate, is then moved toward the left, 
till the vertical beveled edge just touches the extreme 
right-hand end of the diagram. The diagram shown in the 
cut represents the proper location which should exist when 
these preliminary adjustments have been completed. The 
slide at the bottom of clamp K fits closely, so that the 
application of a slight pressure with the thumb or finger is 
required to displace it. 

The beam of the instrument is next placed on the board, 
with the pin at the lower end resting in the groove /, and 
the weight Q applied to the top of the pin so as to keep it 
securely in place. The tracer O is moved to the right-hand 
end of the diagram and set at the point D, on the line of 
the diagram, where the clamp K and the diagram touch 
each other. Here a slight indentation is made in the paper 
by pressing the finger on the top of the tracer, and this 
serves as a starting point. The graduated wheel is next 
turned so as to bring its zero mark to the zero mark on the 
vernier. The instrument is now ready for operation. The 
tracer O is carefully moved over the line of the diagram, in 
the direction of motion of the hands of a watch, and con- 
tinued till a complete circuit is made and the tracer finally 
reaches the starting point D. Keeping the eye on the 



142 HAWKINS' INDICATOR CATECHISM. 

THE COFFIN AVERAGING PLANIMETER. 
wheel, the tracer is now moved upward by sliding it along 
the edge of the clamp K, until the reading on the wheel 
returns to zero. Another light indentation is made in the 
paper to mark the new position which the tracer occupies. 
This point is represented at A in the cut. The instrument 
is now moved away, the clamp pushed back, and the dis- 
tance between the two points, D and A, is measured by 
employing a scale corresponding to the number of the 
spring used in the indicator. The distance thus found is 
the mean effective pressure, expressed in pounds per square 
inch of piston. 

The Coffin planimeter determines the desired result with- 
out computation, but it may be used also for determining 
the area enclosed by the diagram. This area is given by 
the reading on the graduated wheel, when the circuit of the 
diagram has been made and the tracer reaches the starting 
point D. The wheel has fifteen main divisions, each of 
which represents one square inch of area. Each division 
has five subdivisions, each subdivision representing one- 
fifth, or two-tenths, of a square inch of area. The vernier 
scale enables the subdivisions to be read to fiftieths, each 
of these fiftieths, therefore, representing two one-hundredths 
of a square inch. Having obtained the area in this manner, 
the mean effective pressure may be computed by dividing 
the number of the spring representing the pressure per 
inch in height by the length of the diagram (inches) and 
multiplying the quotient by the area (square inches). In 
first placing the indicator card under the clamps, care must 
be observed that the ends of the diagram set a little away 
from the edge of the clamp, so as to allow for one-half the 
diameter of the tracer, and to bring the centre of the tracer 
over the centre of the line of the diagram. 



HAWKINS' INDICATOR CATECHISM. 143 



EXPLANATION OF TABLES. 

Table I, in the respective columns, gives: I, the tem- 
perature ; 2, heat units ; 3, latent heat ; and 4, density of 
the steam, at certain pressures. 

To use the table, find the given pressure in the first col- 
umn, under " Absolute pressure per square inch, and read 
the corresponding property under the head needed. 

For example : if the weight of a cubic foot of steam at 
90 pounds pressure is to be found, find 90 in the first col- 
umn, and follow the horizontal line, at the same height as 
90, to the last column. The figure found here, .2098, is 
the weight of one cubic foot of steam at 90 pounds press- 
ure, expressed in pounds. 

Table II shows at a glance the mean effective pressure, 
if the point of cut-off and the absolute pressure is known. 

In this table no account is taken of clearance and com- 
pression, but for ordinary figuring the results are sufficiently 
accurate. 

The absolute pressures are shown in the first column, 
and the corresponding mean effective pressures at different 
points of cut-off are given in the other columns. 

If, for instance, the mean effective pressure at an abso- 
lute pressure of 115 pounds (100 pounds gauge pressure) 
and \ stroke cut-off is to be found, proceed as follows : 

Under the head, ''Absolute pressure cut-off ", find 115, 
and follow horizontally to the column under the head 5. 
These heads indicate the number of times the steam is 



144 HA WKINS* INDICA TOR CA TECH ISM. 

EXPLANATION OF TABLES. 

expanded, at corresponding cut-off, i. e., the ratio of expan- 
sion. 

At an absolute pressure of 1 1 5 pounds the M. E. P. will 
be found to be 60.03 pounds, if the engine cuts off at \ 
stroke. 

From this result has to be subtracted the exhaust press- 
ure, above an absolute vacuum. 

Table III is used for the same purpose as Table II ; the 
difference being that it gives "the constant', to be multi- 
plied by the total steam pressure in the cylinder at the 
point of cut-off, to obtain the total mean pressure. 

In Table II the total pressures from 50 to 195, at 
intervals of 5 pounds, are given, but Table III can be used 
to find the mean effective pressures at less than 50 pounds, 
or more than 195 pounds initial piessure, also at all other 
pressures. 

Table IV. In this table the number of pounds of water 
the engine uses per horse power per hour is found, if the 
terminal and the mean effective pressure is known. 

To use the table, locate the terminal pressure above 
absolute vacuum, as indicated by the diagram in the first 
column, and follow at the same height horizontally, to the 
column under the given mean effective pressure. 

Example: Terminal pressure = 16 pounds absolute; 
M. E. P. = 35 ; the water consumption per I. H. P. will be 
16. 14 pounds per hour. 

Table V gives the horse power at 100 ft. piston speed, 
and with one pound of mean effective pressure. 



HAWKINS' INDICATOR CATECHISM. 145 

EXPLANATION OF TABLES. 

To obtain the horse power: Multiply the constants 
opposite diameter of cylinder by the piston speed, and by 
the mean effective pressure, and divide by ioo. 

The result is the horse power. 

Example : Diameter of cylinder — 52". Piston speed 
= 650 ft. per minute. M. E. P. = 35 pounds. Constant 
of 52 = 6.43. 

6.43 X 650 X 35 



100 



= ijl6 3 H. P. 



USEFUL DEFINITIONS. 

A " Constant " may be defined as a " constant multi- 
plyer," which is obtained by careful calculations and as- 
sumed to be surely correct. 

A Heat Unit is that which is required to raise 1 lb. of 
water (at 39 Fahr.) 1 degree. 

Mean Effective Pressure (M. E. P.) is the average force 
of the steam in the cylinder. 

A Pound of Steam is the same as a pound of water and 
steam weighs according to the pressure at which it is held. 

Absolute Pressure of Steam is the same as " total pres- 
sure above vacuum " to obtain " gauge pressure " 15 
pounds per square inch must be subtracted, that being the 
weight of air at the sea level. 



146 HAWKINS' INDICATOR CATECHISM. 



PROPERTIES OF SATURATED STEAM. 
TABLE I. 



Absolute 


Temperature 


Heat units, 


Latent heat 


Density or 


pressure 


in 


from zero, 


in 


weight of 


per sq. in. 


degrees. 


per lb. 


degrees. 


one cubic ft. 


Lbs. 


Fahr. 




Fahr. 


Lbs. 


i 


102. 1 


1 145 


1042.9 


.0030 


2 


126.3 


1152.5 


1025.8 


.0058 


3 


141. 6 


1157.1 


1015 


.0085 


4 


153.1 


1160.6 


1006.8 


.0112 


5 


162.3 


1 163.4 


1000.3 


.0138 


6 


170.2 


1165.8 


994-7 


.0163 


7 


176.9 


1167.9 


990 


.0189 


8 


182.9 


1169.7 


985.7 


.0214 


9 


188.3 


1171.4 


981.9 


.0239 


10 


193-3 


1172.9 


978.4 


.0264, 


ii 


197.8 


1174.2 


975-2 


.0289 


12 


202 


H75-5 


972.2 


.0314 


13 


205.9 


1176.7 


969.4 


.0338 


14 


209.6 


H77-9 


966.8 


.0362 


14-7 


212 


1178,6 


965.2 


.0380 


15 


213. 1 


1178.9 


964-3 


.0387 


16 


216.3 


1179.9 


962.1 


.0411 


17 


219.6 


1180.9 


959-8 


.0435 


18 


222.4 


1181.8 


957-7 


.0459 


19 


225.3 


1182.6 


955-7 


.0483 


20 


228 


1183.5 


952.8 


.0507 


21 


230.6 


1184.2 


951.3 


.0531 


22 


233-1 


1 185 


949-9 


.0555 


23 


235-5 


1185.7 


948.5 


.0580 


24 


237-8 


1186.5 


946.9 


.0601 


25 


240.1 


1187.1 


945-3 


.0625 


26 


242.3 


1 187.8 


943-7 


.0650 


27 


244.4 


1 188.5 


942.2 


.0673 


28 


246.4 


1189 


940.8 


.0696 


29 


248.4 


1189.7 


9394 


.0719 


30 


250.4 


1 190.3 


937-9 


.0743 


31 


252.2 


1 190.8 


936.7 


.0766 


32 


254.1 


1191.4 


935.3 


.0789 


33 


255-9 


1191.9 


934 


.0812 


34 


257.6 


1192.5 


932.8 


.0835 


35 


259.3 


1 193 


931.6 


.0858 


36 


260.9 


1 193.5 


930.5 


.0881 


37 


262.6 


1 194 


929.3 


.0905 


38 • 


264.2 


1 194.5 


928.2 


.0929 


39 


265.8 


1 195 


927.1 


.0952 


4o 


267.3 


1 195-4 


926 


.0974 


41 


268.7 


1 195.9 


924.9 


.0996 


4? 


270.2 


1 196.3 


923.9 


.1020 


43 


271.6 


1 196.7 


922.9 


.1042 


44 


273 


1197.2 


921.9 


.1065 


45 


274.4 


1 197.6 


920.9 


.1089 


46 


275.8 


1 198 


919.9 


.1111 



HAWKINS' INDICATOR CATECHISM. 147 



PROPERTIES OF SATURATED STEAM. 
TABLE I.— Continued. 



Absolute 


Temperat're 


Heat units 


Latent heat. 


Density or 


pressure 


in 


from. zero, 


in 


weight of 


per sq. in. 


degrees. 


per lb. 


degrees. 


one cubic ft. 


Lbs. 


Fahr. 




Fahr. 


Lbs. 


47 


277.1 


1198.4 


919 


.1133 


48 


278.4 


1 198.8 


918. 1 


.1156 


49 


279-7 


1199.2 


917.2 


.1179 


50 


281 


1199.6 


916.3 


.1202 


51 


282.3 


1200 


9J54 


.122^ 


52 


283.5 


1200.4 


914*5 


.1246 


53 


2847 


1200.7 


913-6 


.1269 


54 


285.9 


1 201. 1 


912.8 


.1291 


55 


287.1 


I20I.4 


912 


.I3H 


56 


288.2 


1201,8 


911. 2 


.1336 


57 


289.3 


1202. 1 


910.4 


.1364 


58 


290.4 


1202.5 


909.6 


.1380 


59 


291.6 


1202.8 


908.8 


.1403 


60 


292.7 


1203.2 


908 


.1425 


61 


293.8 


1203.5 


907.2 


.1447 


62 


294.8 


1203.8 


906.4 


.1469 


63 


295-9 


1204. I 


905.6 


.1493 


64 


296.9 


?204.5 


904.9 


.1516 


65 


298 


I204.8 


904.2 


.1538 


66 


299 


I2O5. 1' 


903.5 


.1560 


67 


300 


12054 


902.8 


.1583 


68 


300.9 


12057 


902.1 


.1605 


69 


361.9 


1206 


901.4 


.1627 


70 


302.9 


1206.3 


900.8 


, .1648 


71 


303.9 


1206.6 


900.3 


1 .1670 


72 


304.8 


I206.9 


899.6 


.1692 


73 


305.7 


1207. I 


898.9 


.1714 


74 


306.6 


I2074 


898.2 


1 - T 736 


75 


307.5 


I207.7 


897.5 


.17^9 


76 


308.4 


1208 


896.8 


.1782 


77 


309.3 


1208.2 


896.1 


.1804 


78 


310.2 


1208.5 


895.5 


.1826 


79 


311. 1 


J 208.8 


894.9 


.1848 


80 


312 


1209 


894.3 


.1869 


81 


312.8 


1209 3 


8937 


.1891 


82 


313.6 


1209.6 


893.1 


.1913 


83 


314.5 


1209.8 


892.5 


.1935 


84 


315.3 


1210 


892 


.1957 


85 


316.1 


I2I0.3 


891.4 


.1980 


86 


316.9 


I2I0.6 


890.8 


.2002 


87 


317.8 


I2I0.8 


890.2 


.2024 


88 


318.6 


I2II 


889.6 


.2044 


89 


319.4 


1211*3 


889 


.2067 


90 


320.2 


121 1.6 


888.5 


.2089 


91 


. 321 


I2II.8 


887.9 


.2111 


92 


321.7 


1212 


887.3 


.2133 


93 


322.5 


I2I2.3 


886.8 


.2155 



148 HAWKINS 1 INDICATOR CATECHISM. 



PROPERTIES OF SATURATED STEAM, 
TABLE I,— Continued. 



Absolute 


Tempornt're 


Heat units, 


Latent hertt 


Density or 


pressure 


111 


from zero, 


in 


weight of 


per sq. in. 


degrees. 


per lb. 


degrees. 


one cubic ft. 


Lbs. 


Fahr. 




Fahr. 


Lbs. 


94 


323*3 


121 2.5 


886.3 


.2176 


95 


324. J 


I2I2.7 


885.8 


.2198 


96 


324.8 


1 213 


885.2 


.2219 


97 


325.6 


I2I3.2 


884.6 


.2241 


98 


326.3 


1213.4 


884.1 


'63 


99 


327.1 


J2I v }.(> 


883.6 


.2285 


ICO 


327.9 


I2I3.8 


883.1 


.2307 


101 


328.5 


F2I4 


882.6 


.2329 


102 


329- J 


I2I4.3 


882.] 


.235! 


103 


329.9 


I2I4.5 


881.6 


.2373 


104 


330«6 


I2I4.7 


881. 1 


.2393 


105 


331.3 


I2I4.9 


880.7 


.2414 


106 


331.9 


I2I5.I 


880.2 


.2435 


107 


332.6 


I2I5.3 


879.7 


.2456 


108 


333.3 


I 21 5.6 


879.2 


•2477 


109 


334 


I2I5.S 


878.7 


.2.109 


no 


334.6 


12l6 


878.3 


.2521 


11 1 


335-3 


I2I6.2 


877.8 


.2543 


1 12 


336 


12X6.4 


877-3 


.2564 


113 


336.7 


I2I6.6 


876.8 


.2586 


114 


337-4 


12I().S 


870.3 


. 2607 


115 


338 


1217 


875.9 


.jo..\S 


116 


338.6 


I2I7.2 


875.5 


.2649 


117 


339.3 


1217.4 


875 


.2652 


118 


339-9 


1217.6 


874.5 


.2674 


ri9 


340.5 


I2I7.S 


874.1 


.2696 


120 


341. 1 


I2I7.9 


873.7 


.2738 


121 


341.8 


I21S.I 


§73.2 


.2759 


122 


342.4 


t2i8.3 


S72.8 


.2780 


123 


343 


121S.5 


872.3 


.2801 


124 


343-6 


121S.7 


871.9 


,2822 


125 


3442 


121S.9 


871.5 


.2845 


126 


344.8 


1219.1 


871.1 


. 2867 


127 


345-4 


1219.3 


870.7 


.2889 


128 


346 


1219.4 


S70.2 


..'Oil 


129 


346.6 


1219.6 


869.8 


•2933 


130 


347-2 


1219.8 


869.4 


.2955 


131 


347-8 


1220 


869 


.2977 


132 


348.3 


1 .'JO. 2 


868.6 


---999 


133 


348.9 


1220.4 


868.2 


.3026 


134 


349-5 


1220.5 


867.8 


.3040 


135 


350-1 


1 220.7 


867.4 


.30(H) 


136 


350.6 


1220.9 


S07 


.3080 


137 


351.2 


1221 


866.6 


.3101 


138 


351.8 


1221*2 


S( >f i 


.3121 


139 


352.4 


[221.4 


865.8 


.3142 


140 


352.9 


I22I.5 


865.4, 


.3162 



HAWKINS' INDICATOR CATECHISM. 149 



PROPERTIES OF SATURATED STEAM. 
TABLE l—Continu«l. 



Absolute 


Temperat're 


Heat units 


Latent heat. 


Density or 


pressure 


in 


1 from zero, 


in 


weight of 


per sq. in. 


degrees. 


per lb. 


degrees: 


one cubic ft. 


Lbs. 


Fahr. 




Fahr. 


Lbs. 


141 


353-5 


1221.7 


865 


.3184 


142 


3.M 


1221.9 


864.6 


.3206 


143 


354-5 


1222 


864.2 


.3228 


144 


355 


1222.2 


863.9 


.3250 


145 


355.6 


1222.4 


863,5 


.3273 


146 


356.1 


1222.5 


863.1 


.3294 


147 


356.7 


1222.7 


862.7 


.3315 


148 


357-2 


1222.9 


862.3 


.3336 


149 


357-8 


1^223 


861.9 


•335/ 


150 


358.3 


1223.2 


861.5 


•3377 


155 


36i 


1224 


8597 


.3484 


160 


3634 


1224.8 


857.9 


.3590 


165 


366 


1225.5 


856.2 


.3695 


170 


368.2 


1226.2 


854.5 


.3798 


175 


370.8, 


1226.9 


852.9 


.3809 


180 


372.9 


1227.7 


851.3 


.4009 


185 


375-3 


1228.3 


849.6 


.4117 


190 


377.5 


1229 


848 


.4222 


195 


379-7 


1229.7 


846.5 


.4327 


809 


381. 1 


1230.3 


845 


•4431 



150 HAWKINS' INDICATOR CATECHISM. 



TABLE II. 



©•^G©TH^t>^©l>CO©©CO©©C1©innia5iniHO&«*f-<t*.T}4©t>cn 

woioiow^^Tticocoojw^THrtrHqoooiOsoioooogot^b-^oo 
^dHNco^ic*©!^ oo*c" o-«-h cz co"«# in co t^ i>* 06 c^ © ^ c<i co* -<* in co !>*• 

OiHHHHHHHHHH(N(N(NO)(M(M(M(NW(M(NCOCOCOeOCOCOM» 

oooooooooooooooooooooooooooooo 
© © © o.o ooooooooooooooooooooooooo 

OrH<>5c0^lCOt>Io6o50r4(>ic^^lOl^t^00050i^c4o^^lO 
HHHHHHriHHH(N(NCa(N<N(N^(N(^(NCOMCC)COW«C0COC0eO 

W00C<lW0iWO05MOOWl>6THl>H4H00^W00<Nl0OCT«001C0O 
CO CO ^ ^ ^ IC I O U5 O CO ^ l> t» (» 00 <» C5 05 O O O O H »H r< (N (N W CO CO • 

THtHiHr*iHtHiHrtTHrHCqc*CNC>lC>3<>l<^<^<^C0CO03COCOCOC^ 

OQOO^NO OOCO rHNOQOO'^NOQOCO^fMOOOCD^cqOM^rHIM 

ooooooHi?|wco^ioo^^ooQqqHWco^^ioi©t>xoociori 

rHiH»HrHT^r^rHr*riOl<NC<lC>lCq<^<^<?ICqiC0C0C0C0C0C^ 

©T-IC<ICOTHincot>0c|c5 ©~*-T<M COtH lAONOOOlOHcqcO^io^lXiOOi 
tH Ol CO # Tin in CO t^ 00 Oi : © OJ CO rJH iO CO l> 00 OS QHW^iOqt^OOOlprHlM 

rH cq co rj* in co t>^ od OS T-H ci co* t* m* cd i>* oo © r-3 <n co* rj* in* co t> od © r-J OJ* CO 

r-l i-< r-f r-l rHiHiHi^rHCT^^CTCq^CTC^i^lCOCOCOCOCOCOCOCOCOTrl'*'^ 

m|<N Ot»W(MOl>W(MO b- m (MOt«W«OI>W(MOMn(MONW?l 
t>l© H ,.^ ^ ^ 0O ft H CO 1C CO 00 O (>J CO lO b; O O W rJJ O ^. 05 H CO ^ co a> 

W00NW05«OftMOOC0t*O^SHrH00HW00CNlC05C<IC00iC0O 
CO»qOOOC<llCI>-00<^lTtJt^Oi^^CDOqrHCO»OOOOC>liqt> ©,<M rft CO © r-* 

cicO*r^COI>o6o^C*05CO*r^lO*t^odoiOCTCO^lOl^o6o^OrHCO 
THrHiHrHT^rtMCq<^<^«NC<l<^<NC^COCOCOCOCOCOC0CO^Tj<T^^rt<T}<^ 





O rH 00 'b* C0O^00<MC0O'rH00<MC0O^00<MC0O'^00<MC0O'*00C<lC3 

^0)^qwHq^i>(Noococx)^qiooiOHqwb;(Noocoqi|Qwq 
incood©"r4eo*T*co't^©o'c^co*incdoo'©i^co*T*cd 

rH.iHrt(^C^CNC<l(^C>lC>ICOCOCOCOCOCO^^^^Tt<T^^lC^3lOlOWiacO 




O(MtHc000P(^^O00O<M^ CO 00 © (M^COOOOCI'f ooo6(M^«ooo 
o<i th o © oo oo i> co in ^ r^ co c>i rH © o © oo i>- cq co in ^ co ^ 
c**H<w^cdooocrf^cdoo'o(^T|*co*oo'o^THcowi>"CT*rHW 

T^(^G<l<NC>?C>lCOCOCOCOCOrt<^^^rJ<^IOU3lOiOlOCOCOCOCOCOI>»I>t^ 



ooooooooooo © © © © © ©©©©©©©©©©©©©> 

_rHC^C0^C5C0I>C»OOr^03C0r^l0C0t^00O©TH<N 

»-* co* in* i> a* rH ci in t>* os o* h* co op" ©" o*'* <x>oo"©'cdin*t>^©*^co*»ni>©a"I 
(^wc^c^ic^cococococoT^TjirjiT^ioioiouaiocoococp^t-t^i^i^i^i^ 



C<lC>*C^COCOCOCOCO^^^^inininincDCOCOCOCOt~C~fc"-t-0000QO00C 



CO00-*COCO©i-i"^CO© (M^NOtMWt>HCOU5000COCOOOHCOC005^ 
<^<^COCOOOCO^T+H^"<*lininincOCOCDOC'-C^t--C~C© 00 .00 00. OS C5.© OS ^ 



ITS CO <M © © t-.cp rt«eO^H©O0t»lOTH<MrHCi00©m.<M(M©m'W>n'*"*.Tjl 

«(»oqoot>N^i>r>i>t*qqqqqcowwwioioioin^^^ '^^ 
oc4in*odr4^^©cocda5<^inoo*^^i>*©co*cD©<>*in*o6o 

<MCOCOCOTj<THT^lOlOiniOCO©COt»t't^00 000000O»a5Ci tH.tH r-l rH rH f-4 



* £ 



©in ©\n©m© in©in©in©in©in©m©m©in ©'*n © in© m ©in 
tn in cpcp^t»a?oocics©©r^rH<^<Nc^ro^r^»nincocot>-i^(X)c»aia3 



HAWKINS' INDICATOR CATECHISM. 151 



TABLE III. 



6D- 


06 <E 


_ 


a 


Eh 


o 




a js 


00 


=3 £ 


z a 


a 


.a »0 

o «j 


1 a s 


a 


TO 7* 

D 2 


1 - 1 

§ * « 


S S 


£3 «S 




3 « 


8 1 


a * o 

3 0) £ 


09 ^ 

ft 3 

Sj .2 


ft 


£ 


S 


7 
8 


1* 


992 


3 


H 


966 


3 


H 


.937 


5 
g 


11 


.919 


1 


2 


.846 


3 


2| 


.743 


1 


3 


.670 




4 


.597 


i- 


5 


.522 


1 


6 


464 


4 


7 


.420 


"8 


8 


.384 


1 


9 


.355 


rV 


10 


.330 


ft 


11 


.308 


ft 


12 


.290 


ft 


13 


.274 


ft 


14 


.259 


ft 


15 


.247 


ft 


16 


.235 


ft 


17 


.222 


ft 


18 


.216 


r 1 ^ 


19 


.207 


ft 


20 


.1998 


ft 


21 


.193 


ft 


22 


.186 


ft 


23 


.180 


ft 


24 


.174 


ft 


25 


.169 


ft 


26 


164 


ft 


27 


.159 


ft 


28 


155 


ft 


29 


.151 


ft 


30 


.147 



152 HAWKINS' INDICATOR CATECHISM. 



TABLE IV. 



O O Ol'lO tO d'rtf © lO'tO S'^.'MOWWNOMWOWlflNWO 

onaowcHWOH© i-^to osco^os^oooi-^aooiioooi-^io 
^^© i o'co^©o6©©oico^©^o6©^co^iot^odos'i"-"c4 

t- 0> »-« tH t-H.i-t rHfHi-lOf<NOICIC>OIC<lCOCOeOCOCOCOCOCO'^<<»< 

©©C0©©0000t»«O»-<tO •<*© ©-*l^-«*<4O00t*CO©iOOI-<OI© 
©^^C3I>Olt>;Olt>;OltOt-JlO©^aO:Nt^rH©OSi-<0001©©^ 

©00©THiHiHr*rH»H010IOIOIOICIOICOCOCOCCCOCOCOT|<<<t<'>*<'<*< 

0(NHOowojw.q^Hifl^.?DHcoi-i«)H<j:(N<flOcooinco'i| 
^ .©^co^©"o6©^*oicoior^a6©^eo^©i>^05©cicoio«o 

t»00HHHHHrii-l(N(M(MD«(N(MMMMCOMCO0:'*^^^'^ 
<Nrt«t*t>OWOOOlOMC^HOO WNWt-MOONNWOl^^N 

dco«d«owN05in<-<^eoaiT((Oix>Hi>wo50ooiiooiflOO- 
^^°.©oi^ioi>*od©"o*co\iis©*co^^eo^©i>*oo*©o"^toi>ao 

IOt>©THrHrt,Hr^r^CaOIOlOIOJOlC0C0C0e0C0C0C0'<J<'<*''*'«*'<*«''1< 

OSrf©00©©-HCOlO©00-*00©IO©tO©00-JtOt>'-'©t-©IOtOtO 
OS 00 t>- ^C3051>-Tl<iH00lOOlt^©OI©tOOlE~tO»-<0qC0OS©Ola000© 

co to t^ © -^ oi rji © oo os ^ co *£ © 06 os *-* co ^j5 ©o6osi-*oih<©ooos.-". 

rtHH-^HHCQlM(NN« OI 00 COCOCCCOeO'^'o*<^'^"<^^iO 

00©r^.tO-*©t~00©©i-*i-IOI© ©CO t>- «-<«00 ©CO©t~©<MCO©©W 
©©T*©O000©"<S<COi-«©t>-''^ © © t>"^d©©'*Ji-<0»l»«©t>COCS . 
^^^l5-^^WlO^O©*C^Tji«006©^CO*^©o6©»MCO»Ol>OC©^ • 
<M^©0O©THr-lr-.i-lTH<MCN<M<M(M£M COiCO COCOCO-tf^^^^^tOtO 

d©tOiOCOtO©"^lO©»OlOI^CO ©©d©©IO©00©00C0 tO ©© 

OS tH 00 LO IO "^ "^ CO C<{ rH © ©l> tOlO"«*OI ©00 ©tO COCO OS t-;© if r-4 : . 

.^^^^©<NTp©od©oacoiot^as^coto©o6©<N^iot>©^'co ■ ■ 

OI^©aOrHT-li-i»-ti-iOI010lOI010lCOCOCOCOCO"<*<Tj<-T£-^^"T*<lOiO 
t-©©0O©0O0O©COWt»0O"*©©"*0O<M©©©©i-l©«!*<t>- 

cqcsi>u5HHCicoeoweoneoHCONHiH0 050»C5<Dioio .... 
'*t^ a 5 < P»-H co 10 t^oir-5 co toi> os -*co torsos© eo >*j*©o6©oi • • • • 

©©©OJfH©COt^COOO^t"«tOOOiOi-ICOt~©00©OOWeO© 
rH05CO©00©0?C010©OOOS©©<NeO©r^tOTi<©©00©t- 

""?■** t^os i-J-^ ©oo©oi ^ © os©*co to'© osi-Ico'io t>^os»-*co 

© © ©,©""# -*<M^H©©0Ot^OO-^t«-t>t»t*t-0O0Ot*© 

lO <M OO'OI ©05C0©0SOJ^I>-C5©^©00©OIC0©00r-« 

*"! **. "^"V© oi^i>^05i^^©'o6©*eot6^asoi-Tj'©'oo©co 

OIIOt>i-liHTHr-(i-tOIOIOIOICOCOCOCOCO , *"<*''«J<'^tOtO 
t~tOIO©©©IOi-lh-COt~01©©©iOOI©eO©aO© 

"* ©"*©©© to © •** os co 00 i-t-n<©co t>.©-<^ ©»-jua 

^"^^ »■* eo©od^cotooo©eotoo©©cq»oi>ose?^ 

«WQOHrtHi-i<M«<NiN COCO COCO ^ -<* -* t* ^ tfi> to 

CO0O'*©©CO00<Mh»CM©©©CO<Nt-©"^0O^-i 

l^CO 00|>.©,OI OS ©OI OS WOJt>i-j OStJJ© to ©to 

■""1 '"1 °^ ^h ■*£ t> 06 oi to !>"• © co tooo©«o ©od»-co 

CO © 00 r-l iH iH rl CI OI OI CO CO CO CO T* "*Ji r»< x*< tO tO 

IO©COCO©t : -IOOIOOtO©i-l©©'*OSTj<©^ 

CO©t-0000©©iOCOOIi-lOseOCOeO©00©. CO . . , 

^ © OS <M* tO OO -H •xj*' t>*- ©* CO lO OO r-J -<f t^ Os <N tO ••••«» 

CO y-i r-t iH OI Ol Ol CO CO CO CO •<* TT ^ •"* tO tO 

to ^ '^ ©'*t»-'^t*©r-jeotOCO©'*CO 

«*to©©oico©t> 00© ^HC^OiCs^coco...... 

^^©^^©^©oscotooscqtot^-^^'** • • • 

eJt-HHHW G*9*G*CQ CO CO "* xp th «o 10 

d0000©t»~«00©3©©CO©00t~^Hi-« 
^©©rlJOS^OS'^OOCOt^r-J^tOOJiO . . . . • . 

■^t^i-i tooooi to oso* ©os co©* os co.© •••■•• ."*•••**•• • 

HH i-i Ol <M<NCOCOCO^>^-^tOtO 

^* 00 1> ^^^©©oo^co^cito© 

00 00 OS »-< © OS 00 ©IOCO fH OS to©.- . ......... » . . 

1 ^a6<Nt^'-^ , <J*a6ei©©'^*i>".i-*io - * 

tH v* iH Ol Ol CI CO CO "^ -^ Tfl to to 

00©©IOOI©t-t>.t*t~©U0 

tOOS©Cl©©TjJt^©CO©OS 

"■J os ^H os co 06 oi © »-" to os co • * '• •' * 

lO -»H i-l <M OI CO CO "^ ■** ""* lO 

^»-t©©©THi-ICO«^©tOi" 

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^^©oit^oit^oi©-*©' «• 

t~OI©©«-llO©eO© 

ooco-^j©©coco©t>. . . 

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tot^©©©oioo© 

CI OS CO 00 © 00 OS 00 . . . .- , . . 

06 10 eo © t>* -tJ* i-i od * * 

i-( CI CO CO t*< to to 



§ 5 



^cico^»«©i>oo©©^«co^to©r»<»©©^ci«o^jto©t-ooos© 

MHHMHHHHHHCI91CI CI d CI CI CI CI CI CO. 



HAWKINS' INDICATOR CATECHISM. 153 



TABLE IV.— Continued. 



co* 
W 

& 

CO 

to 
W 

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PH 

H 
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fa 
fa 

w 
55 
w 




ooocoMoo^csHCi^N^nHwocDOcoLooeo 

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OHHHHHHHHrtHHHH(N(NN(N?J(NC^<N(N 


co 


lOO-^COt>.0'-^OOt*OOOOlOuOOOiC7500^00lrtOCO"«^"^ 

c^ c<i co 10 ojrt o ^ tij rt eft t> io ih en i> w in o t> in N co co 
^^Oi^c^co^^incdcdt>"cda"cdo^cicdco^inincd 

C5CJHHHi1HHHH.HHHmH<N(N(NlMlN(M<N(M(N 


CM 


ot*toot*w^(McD?D(»wcft«©NcoaoHt-HWin 
ioc^ocow^^ocowcoHCOTj|^^qi>wcoocococo 
"*. oi-ii-HcMcd^inincdi^oo^cd©i-"cMcM'cd^inincdt^ 

05Hi-iHHHHHrHrtHHHrt!M(MW(N(M(N!NN(M(M 


"tfl 


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QHHHHHHHrtHHHHWOJNWfNCNlCNIWfN^N 


O 

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t» CO !>• CD CO CO i-H CD t~ CO CO CM © <3> W ^ CO H rt| Cft Ifl CO H Ol I> 

®^OrHc^co^^incdt^oo<^oo^c^co"^*^incdr^i>^co 

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CO 


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P5 tH t-I .-4 i-t i-l i-l i-( i-l i-l iH t-1 i-l CM CM CM CM CM CM CM CM CM CM CM CM 


00 
CO 


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Lo^coiMoocooo^cooioajt^cDincoHcnoit-incooi 
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©HHHHHHHHHHHNNNlNC^WCXItNfNC^CNCNlCO 


co 


H'coaOHNHCqcOTHlNOlflCOOCO^OOOJt-inNNO 
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154 HAWKINS' INDICATOR CATECHISM, 



Engine Constants at ioo feet Piston Speed, and One Pound 
Mean Effective Pressure. 

table v. 



Diameter of 


Constant 


Diameter of 


Constant 


Cylinder. 




Cylinder. 




4 


.03787 


26>£ 


1.669 


*H 


.04818 


27 


1 734 


5 


.0594 


27 > 2 


1 795 


5^ 


0718 


28 


1.865 


6 


.0856 


28^ 


1 933 


e>v Q 


.1004 


29 


2 002 


7 


.1166 


29 y 2 


2.070 


t l 4 


1338 


30 


2 141 


8 


.1523 


30 >2 


2 214 


*H 


.1718 


31 


2.287 


9 


1927 


31 % 


2.330 


9> 2 


.2148 


32 


2 437 


10 


.2380 


32H 


2.513 


103^ 


2623 


33 


2 592 


li 


.287K 


33 £ 


2.670 


11 v 2 - 


.3145 


34 


2751 


12 


.3421 


34 \L 


2 832 


12% 


.3718 


35 2 


2.915 


13 


.402 


35 \ 


2 999 


13^ 


433 


36' 


3.084 


14 


.466 


36^ 


3.170 


14J^ 


.500 


37 


3.258 


15 


.535 


37^ 


3 346 


15>£ 


.571 


38 


3 433 


16 


.609 


38^ 


3 527 


lfiX 


.648 


39 


3 619 


17 


.687 


39K 


. 3.713 


n i A 


.728 


40 " 


3.807 


18 


.770 


41 


4.000 


1«X 


.814 


42 


4.197 


19 


.859 


43 


4.400 


1^ 


.905 


44 


4.606 


20 


1951 


45 


4.818 


20^ 


1 001 


46 


5.033 


21 


1.049 


47 


5.254 


2l >9 


1.100 


48 


5.481 


22 


1.151 


49 


5.714 


22^ 


1 204 


50 


5 950 


23 


1.258 


51 


6.190 


23^ 


1.314 


52 


6435 


24 


1.372 


53 


6.687 


24»h 


1 424 


54 


6.938 


25 


1.487 


55 


7.199 


25> 2 


1 547 


56 


7.433 


26 


1.608 


57 


7.730 



HAWKINS 1 INDICATOR CATECHISM. 155 



Engine Constants at ioo feet Piston Speed, and One Pound 
of Mean Effective Pressure. 

TABLE V.— Continued. 



Diameter of 


Constant. 


Diameter of 


Constant. 


Cylinder 




Cylinder. 




58 


8.006 


103 


25.249 


59 


8.284 


104 


25.751 


60 


8.567 


105 


26.239 


61 


8.855 


106 


26.748 


62 


9 148 


107 


27.248° 


63 


9.446 


108 


27.757 


64 


9.748 


109 


28.276 


65 


10.055 


110 


28.798 


66 


10.367 


\\\ 


OQ 323 


67 


10.683 


29*854 


68 


11 005 


113 


30.390 


69 


11.330 


114 


30.930 


70 


11.661 


115 


31.475 


71 


11.997 


116 


32024 


72 


12.368 


117 


32.579 


73 


12 683 


118 


33 139 


74 


13032 


119 


33 703 


75 


13.387 


120 


34 272 


76 


13 746 


121 


34.542 


77 


14 110 


122 


35.423 


78 


14 479 


123 


36.007 


79 


14.848 


124 


36.595 


80 


15.232 


125 


37.182 


81 


15.606 


126 


37.784 


82 


16 003 


127 


38387 


83 


16.396 


128 


38,993 


84 


16.793 


129 


39.605 


85 


17.195 


130 


40.222 


86 


17.602 


131 


40.825 


87 


18.014 


132 


41.409 


88 


18.430 


133 


42 098 


89 


18.851 


134 


42.735 


90 


19.278 


135 


43.678 


91 


19.708 


136 


44 023 


92 


20.141 


137 


44 669 


33 


20.584 


138 


45.324 


94 


21.029 


139 


45.984 


95 


21.479 


140 


46.678 


96 


21.933 


141 


47.317 


97 


22.393 


142 


47.990 


98 


22.857 


143 


48.066 


99 


23.326 


144 


49.353 


100 


23.800 


145 


50.003 


101 


24.278 


146 


50.701 


102 


24.761 


147 


51.429 



INDICATOR DATA. 



INDICATOR DATA. 



INDICATOR DATA. 



INDICATOR DATA. 



INDICATOR DATA. 



INDICATOR DATA. 



INDICATOR DATA. 



INDICATOR DATA. 






INDEX 



TO 



HAWKINS' INDICATOR CATECHISM. 



Absolute Pressure of Steam, Defi- 
nition, 19, 145. 
Adjusting Indicator, 34, 35. 
Admission Line, 55-58. 

Note, 58. 

Example of, Ills., 56, 70, 71. 
Air Compressors, Indicating of 87-88. 
American Steam Gauge Co., Revo- 
lution Counters, 76. 
American-Tnompson Indicators, 10. 

Attached to Reducing Motion, 30. 
Amsler Planimeter, Ills., 133. 
Atmospheric line, 34, 73. 
Advantage in TJse of Revolution 
Counters, 76. 

Average Pressure, 107. 
Bachelder Indicator, 93-95. 

Attached to Reducing Motion, 30. 

Illustration, 94. 
Back Pressure, Definition, 31. 

Line, Ills., 68. 

Note, 53. 
" Bad Card" or Diagram, Ills , 80. 
Barrel, Putting Paper on, 43. 
Base line, Adjustment of, 34. 
Boiler Pressure, Impossible to Main- 
tain, Note, 59. 



Buckeye Engine Co.'s Reducing 
Motion, 39. 
Cross Compound Diagram, Ills., 

115-118. 
Diagrams, 78, 119-131. 
Buffalo Indicator, 101, 103. 

C, Abbreviation for Crank End, see 
Note, 111. 

Care in Closing Indicator Cock, 73. 

Circuit Closer Fitted to a Crosby 
Indicator, 49. 

Clearance, Definition, 31. 
Line, 75. 

Clearing Indicator after Use, 50. 

Coffin Planimeter, 140-143. 

Compound Engine, Ills., 4. 

Compression line, 69-71. 

Condensing Engines, Adjustment 
for, 34. 

Connecting Paper Brum to Instru- 
ment, 43. 

€i Constant," Definition of, 115. 

Constants, Engine, Tables, 154-155. 
Mean Effective Pressure, 151. 

Card, Best Length of, 37. 

Card-Pin, Distance from Fulcrum of 
Lever, 37. 



Index. 



Corliss and Nightingale, Diagram, 

A. D. 1851, 78. 
Counters, Revolution, 76-77. 
Crosby Indicator, 103-105. 

Fitted to a Circuit and Closer, 49. 
Fitted with a Sargent Electrical 

Attachment, 49. 
Crosby Locomotive Engine Counter, 

77. 
Crosby's Flanimeter Attachment, 

133-134. 
Crosshead of Engine, Movement of, 

53. 

Dedication of Worfc, 3. 

Definitions, Useful, 145. 

Density of Steam, 146. 

Devices for Measuring Diagrams, 

Ills., 110. 
Diagram, Buckeye Engine, 78. 

Corliss & Nightingale, A. D. 1851, 78. 

Elementary, Ills., 107. 

From Air Compressor, Ills., 87. 

From Porter-Allen Engine, Ills., 83. 

From Westinghouse "Junior" En- 
gine, 83. 

Ills., of Ideal, 111. 

Ideal Indicator, Ills., 52. 

Indicator, 11, 21, 52, 54. 

Indicator, What it Records, 106. 

Measuring Length of, 130. 

Measuring by Ordinates, 106-121. 

Theoretical Indicator, 52-53. 

Watts-Campbell Corliss Tandem 
Engine, 112, 113. 

Watts-Campbell Engine, Ills., 82 

Devices for Measuring, Ills., 110. 

Examples of, 78-86. 

From Locomotive Engines, Ills., 85, 
86. 

Buckeye Cross Compound Engine, 
Ills., 115-118. 
Distance of Card-Fin from Ful- 

cram of Lever, 27. 
Drum Stop Motions, 44-46. 



Electrical Attachments for Indi- 
cators, 46-49. 
Engine "Constants," Table, 155. 
Engine, Perfect, Ills., 81. 
Examples of Diagrams, 78-86. 

Of Measuring Diagrams by Ordi- 
nates, 111-121. 
Exhaust line, 67-68. 

Notes, 53, 54. 
Expansion Curve, Never Equals the 

Theoretical Curve, 62. 
Expansion line, 61-62. 

Ratio of, Definition, 21. 
Explanation of Tables, 143-145. 

Figuring Steam Consumption by 

Diagram, 74-75. 
Finding Mean Effective Pressure 

by Flanimeter, 130. 

Gas, Law of Expansion, 61. 
Gauge Pressure, 19, 145. 

H., Abbreviation for Head End, Note, 

111. 
Haughtaling Itcducing Motion, 30- 

36. 
Hawley, Thomas, Quotation, 8. 
Heat, Latent, 146. 
Heat Unit of Steam, Table, 146. 
High Speed Revolution Counters, 

77. 
H. P., Abbreviation for Horse Power, 

Note, 111. 

Ideal Diagram, Ills., 111. 
Ideal Indicator Diagram, Ills., 52. 
Ideal Reducing Wheel, 30. 
Indicating JLir Compressors, 87-88. 
Indicating Locomotives, 84-86. 

Advantages of, 85. 
Indicator, Adjusting, 24-25. 

An Instrument or Machine ? 17. 

American-Thompson, 10. 

Attachments, Electrical, 46 

Pneumatic, 49. 

Bach elder, 93-95, 






Index. 



Indicator, Buffalo, 101-103. 

Cards, Taking of, 43-51. 

Card, Tracing of, 53. 

Care of, 18, 19. 

Cleaning of, after use, 50. 

Cock, Care in Closing, 72. 

Crosby, 103-105. 

Diagram, 11, 21, 52, 54. 

What it Record?, 106. 

Six different Operations represented 
by Lines, 52. 

Does no Work, 17. 

Drum, Description, 10. 

General Description, 9. 

History of Watts, Note, 22. 

Essential. Parts, 16. 

Lyne, 100, 101. 

Lost Motion in, 14. 

Lubricating, 26. 

Operation of, 12. 

" Outfit," 22. 

Parts to be Closely Observed, 18. 

Pencil, 13. 

Piping Up, 18, 37-42. 

Preparing for Use, 23-26. 

Purpose or Use of, 9. 

Shop Names of, 16. 

Size of Piston, 10. 

Specially Important Uses of, 17. 

Spring, Ills., 10, 19. 

Tabor, 89-92. 

Thompson's Improved, 96-99. 

When More than One is Needed, 22. 
I. P., Abbreviation for Intermediate 

Pressure, Note, 111. 
Initial Pressure, Definition, 20. 
Introduction, 10. 

Latent Heat, Table, 146. 
Law of Expansion of Gas, 61. 
Lever Meducing Motion, 27-29. 
Lever, Supplementary, 28. 

Total Length of, 27. 
Line, Admission, 55-58. 

Atmospheric, 72. 



Line, Clearance, 73. 

Compression, 69-71. 

Expansion, 61-62. 

Of Perfect Vacuum, 72. 

Release, 63-66. 

Steam, 59-60. 

Exhaust, 67-68. 
Lippincott Planimeter, 131-132. 
Locomotives, Advantages of Indicat- 
ing, 85. 

Indicating of, 84-86. 
Loop, Negative, 65-66. 
L. P., Abbreviation for Low Pressure, 

Note, 111. 
Lost Motion in Indicator, 14. 
Lubricating of Indicator, 26. 
Lyne Indicator, 100-101. 

Mean Effective Pressure, 23, 106. 
Constants, 151. 
Tables, 150. 

M. _E. P., Abbreviation for Mean 
Effective Pressure, 111. 

Measuring the Diagram by Ordi- 
nate s, 106-121. 

Measuring Length of Diagram, 130. 

Momentum, Effects of, 23. 

Motion of Indicator Drum, 10. 

Movement of Engine Cross Head, 
53. 

Negative Loop, 65-66. 
Note, an Unwritten Law, 16. 

Indicator does no Work, 17. 

Relating to Terminal Pressure, 20. 

Relating to Pencil Pressing too 
Tight, 18. 

Oil, Machinery, 22. 

Operation of the Indicator, 12. 

Ordinates, Measuring the Diagram 

by, 106-121. 
« Outfit," Indicator, 22. 

Paper -Drum, Connecting to Reduc- 
1 ing Motion, 39. 



Index. 



Pantograph, The, 29 ; Ills., 31-33. 

Application of, 33. 
Parts of Indicator to be Watched, 

18. 
Pencil, Indicator, 13. 

Finishing Point with a File, 42. 

Mechanism of Tabor Indicator, 90. 

Selection of Kind of, 25. 
Perfect Engine, Ills., 81. 
Perfect Vacuum, Line of, 72. 
"Piping Up" Indicator, 18,37-42. 
Piston, Pressure upon, Note, 67. 
Planimeter, 22, 122-129. 

Attachment, Crosby's, 133-134. 

Amsler, 122. 

Coffin, 140-142. 

Finding Mean Effective Pressure 
by, 130. 

How to Read, 123. 

Lippincott's, 131-132, 

Robertson- Amsler, Ills., 132. 

Willis, 135-139. 
Pneumatic Indicator Attachment, 

49. 
Porter- Allen Engine, Diagram f rom- 

83. 
Pound of Steam, same as Pound 

of Water. 145. 
Preparing to Use Indicator, 12, 23. 
Pressure, Absolute, Definition, 19. 

Back, Definition, 21. 

Gauge, Definition, 19. 

Initial, Definition, 20. 

Mean Effective, Definition, 20. 

Terminal, Definition, 20. 
Pressure on Piston, 67, 106, 107. 
Principal Parts of Indicator, 10. 
Properties of Saturated Steam, Ta- 
ble, 146. 
Putting Paper on Parrel 43; Ills., 
51. 

Questions and Answers, 1~-21. 

Raabe, Henry, Dedication to, 3. 



, 



Ratio of Expansion, Definition, 21. 
Reducing Mo Hon, 22, 27-29 ; Note, 29. 

Buckeye Engine Co 's, £9. 

For Railroad Locomotive, 84. 

Houghtaling's, 30-36. 

Lever, 27-29. 
Reducing Wheel, Ideal, 30. 

Victor, 30. 
Release line, 63-66. 

Example of, Ills., 64, 65. 
Roberts on- Amsler Planimeter, 132. 
Robertson & Sons Pneumatic De- 
vice, 49. 
Rule for Figuring Steam Consump- 
tion by the Diafjram, 74. 
Revolution Counters, 76-77. 

Sargent's Electrical Attachment, 

48. 
Fitted to a Crosby Indicator, 49. 
Saturated Steam, Definition, 21. 
Scale and Wheel for Planimeter, 

Ills., 132. 
Selecting Spring, 42. 
Shop Names of Indicator, 16. 
Six Different Operations Repre- 
sented by Lines, 52. 
"Slamming " of the Exhaust 

Valves, 66. 
Spanners, 22. 

Spring, Operation of , in Bachelder Ir 
dicator, 93. 
Selecting, 23, 42. 
Changing of, 23. 
Indicator, 19. 

Used in Tabor Indicator, 91. 
Steam Consumption, Figuring by 

Diagram, 74-75. 
Steam, Density of, 146. 
Steam Engine Indicator, Descrip- 
tion, 9. 
Steam, Heat Unit of, 146. 
Latent Heat of, 146. 
Line, Ills., 59. 
Mean Effective Pressure, Table, 150. 



Index. 



Steam, Saturated, Definition, 21. 


Thompson's Improved Indicator, 


Superheated, Definition, 21. 


96-99 


Tables, 146-149. 


Operation of, 98. 


Temperature of, Table, 146. 


T7iree-Way Cock, 22; Ills., 2. 


Stop Motions of Drum, 44-46. 


Tracing of an Indicator Card, 53. 


Superheated Steam, Definition, 21. 






Useful Definitions, 145. 


Tables, Explanation of, 143-145. 




Mean Effective Pressure, 150. 


Victor Heducing Wheel, 30. 


Steam, 146-149. 




Water Consumption, 152-153. 


Water Consumption, Tables, 152-153. 


Tabor Indicator, 89 92. 


Watts- Campbell Corliss Engine, 


Attachment to Reducing Motion, 


Diagrams from, Ills., 82, 112, 113. 


30; Ills-, 36. 


Watts Indicator, Note, 22. 


With Electrical Attachment, 46, 


Westinghoase "Junior" Engine, 


Taking Indicator Cards, 43-51. 


Diagram from, 83. 


TemperaUr+m of Steam, Table, 146. 


Willis JPlanimeter, 135-139. 


Terminal ^"essure, Definition, 20. 


Wire Drawing, Definition, 20. 


Theoretical indicator Diagram, 52- 


Of Steam, 106. 


53. 


Wrenches, 22, 




. . . FOR . . . 

ENGINEERS, 
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Electricians, 
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and all 

Steam Users. 

SEND ALL ORDERS TO 

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Cor. 13th Street, New York- 




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THE KEY to the contents of the Hawkins Books is to be 
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Treatise. 






jfjJIM' Price, $2.00. 


This is a book of 550 pp. , full of up-to-date 
information. 300 illustrations. Handsomely 
bound in red leather, pocket-book form, size 4^ 
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This book has been issued in response to a 
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CONTENTS. 



The Dynamo ; Conductors and Non- Conduc- 
tors ; Symbols, abbreviations and definitions re- 
lating to electricity ; Parts of the Dynamo ; The 
Motor ; The Care and Management of the Dyna- 
mo and Motor. 

Electric Lighting ; Wiring ; The rules and 
requirements of the National Board of Under- 
writers in full ; Electrical Measurements. 

The Electric Railway ; L,ine Work ; Instruc- 
tion and Cautions for Einemen and the Dynamo 
Room ; Storage Batteries; Care and Management 
of the Street Car Motor ; Electro Plating. 

The Telephone and Telegraph; The Electric 
Elevator ; Accidents and Emergencies, etc. , etc. 

The full one-third part of the whole work 
has been devoted to the explanation and illustra- 
tions of the dynamo, and particular directions 
relating to its care and management ;— all the 
directions are given in the simplest and most 
kindly way to assist rather than confuse the 
learner. The names of the various parts of the 
machine are also given with pictorial illustra- 
tions of the same. 

In the Catechism no less than 25 full page 
illustrations have been given of the various dy- 
namo machines made in different parts of the 
country, and an equal number of part pap-e il) as- 
trations. 






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Engi= 

neers 

Exami= 

nations 

with 

Ques= 

tions 

and 

An= 

swers. 

Price 

$2.00. 



The volume is bound (being designed for constant 
and ready reference) in substantial red leather with titles 
and edges in gold; it consists of between 200 and 300 
pages, printed on heavy, fine surface paper; size 5^x7 %"\ 
weight 1 ^ lbs. 

This book is a most important aid to all engineers, 
and is undoubtedly the most helpful ever issued relating 
to a safe and sure preparation for examination. 

It presents in a condensed form the most approved 
practice in the care and management of Steam Boilers, 
Engines, Pumps, Electrical and Refrigerating Machines. 

The following is a complete list of its contents: 




TESTIMONIAL.-FRED. D. STONE, "Inclosed find 
$2.00 for Hawkins' New Catechism of Electricity. I have 
HAWKINS' AIDS TO ENGINEERS EXAMINATIONS. 
It is the best on the subject. I owe my success in securing a 
license to it. 



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Contents.. 



1. This book embraces information not else- 
where obtainable. 

2. It tells exactly what an engineer will have to 
go through in getting a license, with much kindly 
and helpful advice to the applicant for a license. 

3. It contains the annual report of the superin- 
tendents of "Steam Boiler Inspection and Certifica- 
tion of Engineers' for the cities of New York and 
Brooklyn. 

4. It contains various rules, regulations and laws 
of cities for the examination of boilers and the 
licensing of engineers. 

5. It contains the laws and regulations of the 
U. S. for the examination and grading of all marine 
engineers. 

6. It gives a short chapter on the "Key to Suc- 
cess " in obtaining knowledge necessary for advance- 
ment in engineering. This is very important. 

7. The book gives the underlying principles of 
steam-engineering in plain language, with sample 
questions and answers likely to be asked by the 
examiner. 

8. It gives a few plain rules of arithmetic with 
examples of how to work the problems relating to the 
safety valve, strength of boilers and horse power of 
the steam engine and steam boiler. 

9. The main subjects treated, upon which are 
given detailed information with questions and 
answers are as follows : — The Steam Boiler, Boiler 
Braces, incrustation and Scale, Firing of Steam 
Boilers, Water Circulation in Boilers, Construction 
and Strength of Boilers, The Steam Engine, Engine 
and Boiler Fittings, Pumps, The Injector, Electricity 
and Electric Machines, Steam Heating, Refrigera, 
tion s Valve Setting, etc., etc. 



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Maxims 

and 

Instructions 

for the 

Boiler Room. 

Price $2.00. 

Piiilisl 111 

This book is uniform in binding and size 
with ' 'Calculations for Engineers" and the "New 
Catechism of the Steam Engine ' ' ; the size is 
6 x 8^ inches, i}( inches thick; weight 2 lbs. ; 
and bound in green silk cloth, gilt tops and titles 
in gold; it has 331 pages with 185 diagrams or 
illustrations. 

This is of all the Hawkins books perhaps 
the most useful to the Engineer-in-charge, to the 
Fireman, to the Steam user or owner, and to the 
student of Steam Engineering 
— for — 

The work relates to Steam Generators, 
Pumps, Appliances, Steam Heating, Practical 
Plumbing, etc., etc. 



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CONTENTS. 

Fire Irons ; The firing of Steam-boilers ; 
A Chapter of "Don'ts" relating to firing; 
Steam-boiler ; the History and Growth of the 
Steam-boiler ; Upright Boiler ; the Marine Boil- 
er ; The Water-tube Boiler ; The Locomotive 
Boiler ; The Horizontal Tubular Boiler ; Parts 
of the Boiler; Specification for 125 H. P. Boil- 
ers ; Construction, Riveting and Bracing of 
Boilers, with many illustrations and tables for 
calculating the strength of same ; Boiler Makers' 
Tools ; Boiler Fixtures and belongings ; Plumb- 
ing; Piping; Accidents and Emergencies; In- 
dex with nearly 1,000 References, etc., etc. 



No Engineer, Fireman or Steam User can afford to 

BE WITHOUT THIS VALUABLE BOOK, AS IT CONTAINS THE PITH 
AND VITAL "POINTS" OF ECONOMICAL AND SAFE STEAM PRO- 
DUCTION. 

The plan followed in this work is the same as that 
so generally approved in "calculations " ; it proceeds 
from the most simple rules and maxims to the highest 
problems ; it is both a book of instruction and refer- 
ENCE. The carefully-prepared Index contains nearly 

ONE THOUSAND REFERENCES, THUS MAKING IT ALMOST A DIC- 
TIONARY OF TERMS. 



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Hand Book 

of 
Calculations 

for 

Engineers. 

Price $2.00. 



THIS IS A WORK OF INSTRUCTION AND REFERENCE 
RELATING TO THE STEAM ENGINE, THE STEAM BOILER, 
ETC., AND HAS BEEN SAID TO CONTAIN EVERY CALCU- 
LATION, RULE AND TABLE NECESSARY TO BE KNOWN 
BY THE ENGINEER, FIREMAN AND STEAM USER. 

IT IS BOUND UNIFORM WITH THE "NEW CATECHISM 
OF THE STEAM ENGINE" AND THE "INSTRUCTIONS FOR 
THE BOILER ROOM" (SIZE 6x8^ INCHES, WEIGHT 2 
LBS.); IN GREEN SILK CLOTH; PRINTED ON HEAVY, FINE 
SURFACE PAPER ; GOLD TITLES, GILT TOP ; WITH 330 
PAGES AND 150 ILLUSTRATIONS. 

THE WORK COMPRISES THE ELEMENTS OF ARITH- 
METIC, MENSURATION, GEOMETRY, MECHANICAL PHIL- 
OSOPHY, WITH COPIOUS NOTES, EXPLANATIONS AND 
HELP RULES USEFUL TO AN ENGINEER. 

AND FOR REFERENCE, TABLES OF SQUARES AND 
CUBES, SQUARE AND CUBE ROOTS, CIRCUMFERENCE AND 
AREAS OF CIRCLES, TABLES OF WEIGHTS OF METALS 
AND PIPES, TABLES OF PRESSURES OF STEAM, ETC., ETC. 



/ 



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CONTENTS. 

Mechanical Powers ; Natural or Mechan= 
leal Philosophy ; Strength of Materials ; 
Mensuration ; Arithmetic; Description of Alge= 
bra and Geometry ; Tables of Weights, Meas= 
ures, Strength of Rope and Chains, Pressures 
of Water, Diameter of Pipes, etc. ; The lndi= 
cator, how to compute; The Safety Valve, 
how to figure; The Steam Boiler; The Steam 
Pump; Horse Powers, how to figure for 
engines and boilers ; Steam, what it is, etc.; 
Index and Useful Definitions. 



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TESTIMONIALS. 



\ ' I am pleased with the work ; it is of 
value to me. I have charge of a Harris- 
Corliss engine doing 680 H. P. at Slater's 
Cotton Mills." — Cyrus Bucklin, Pawtucket, 
R. I. * * " I think it is the best I ever 
saw, and I thank the day I saw it adver- 
tised." — Jno. C. Robinson, Adams, Mass. 
* " * ' ' The Hand Book is worth its weight 
in dollars to any engineer with common 
sense." — Jas. C. Temple, Eng. , Spring- 
field, 111. 



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New 

Catechism 

of the 

Steam 

Engine. 

Price $2.00. 



A new book from cover to cover, handsomely 
bound in green silk cloth, gilt top, titles in gold; 
440 pages; 325 illustrations; size 6x8^ inches, 
1% inches thick; weight 2 lbs. It is bound 
uniform in style and size with the ' ' Hand Book 
of Calculations ' ' and ' ( Maxims and Instructions 
for the Boiler Room." 

This book is gotten up to fill a long- felt need 
for a practical book. It gives directions for run- 
ning the various types of steam engines that are 
to-day in the market. A list of subjects which 
are fully yet concisely discussed are found on the 
next page. 



v 



CONTENTS. 



The subject matter of the New Catechism of the 
Steam Engine is not arranged in chapters, but ac- 
cording to the more natural order best designed to 
explain at greater or less length the different themes 
discussed. The following are the leading divisions 
of the 480 pages of the book. 



Dedication to Designers and Builders. 

Questions and Answers relating to Steam Engine. 

Foundations for Steam Engine, 

" Parts " of the Steam Engine. 
Stationary Engines. 

Corliss Engines. 

Pumping Engines. 
Locomotive Engines. 

Steam Fire Engines. 

Gas Engines. 
Hoisting Engines. 

Air Compressing Engines. 

Blowing Engines. 
" Compounding. ' ' 

Condensers. 

Marine Engines, 
Valves and Valve Setting. 

" Lining up. M 
Care and Management of the Steam Engine. 
Chapter of "Ifs." 

Arithmetic of the Steam Engine. 



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Bindings. 



Should a finer binding, than cloth, be desired of the 
"Calculations," "Boiler-Room," and " Steam Engine," 
we can supply them in elegant, full red leather bindings 
gold titles and gilt edges — with the other two books, 
which are always bound in "leather and gold," as 
described; this binding makes the handsomest set of 
engineers' books on the market — as well as the most 
useful. 

The extra cost is one dollar per volume (on the three 
books above named) over the cost of the regular cloth 
binding which is also very choice. The leather edition is 
also sold on part payments, separately or together. 



A Few Selected 

Commendations. 

There are no better judges of the true worth of these 
books than practical engineers. The following are exam- 
ples of very many hundreds of recommendations sent 
without solicitation : — 

Jos. S. Hall, Sebo, Mont., " The books are all right and should be 
used by every engineer" ; H. Chambers, Atkinson, Neb., " The value 
of your books is beyond expression, may your good work continue"; 
C. L. Wain, Chief Engineer, Kamloops, B. C, " They are books that 
should be in the hands of every engineer"; Adolph Hahn, St. Louis, 
Mo., " I must say I am well pleased with the books, they are just what 
I was looking for"; T.J. McCartney, Anaconda, Mont., " Accept my 
thanks for the condition and promptness with which you delivered the 
books to me"; T. A. Secord, Unionville, Mo., "I take pleasure in say- 
ing that Hawkins' complete works are a very valuable addition toauy 
engineer's library"; William J. Lee, Machinist, U. S. Steamer Indi- 
ana, off Havana, Cuba, April 26, '98, "'1 he war is on us and so you 
will know the cause of any delay in payments, the men are veiy much 
pleased with the books, they say your books were just what they 
wanted. Two more sets are wanted." 



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Easy Payments. 

The Hawkins' works are sold on easy part payments. 
The set (5 books) are sent upon the following terms : 
Upon the receipt of $2.00 and the promise to pay one 
dollar per month, the books will be forwarded, charges 
prepaid, to the purchaser in any part of the world; should 
one, two, or three books be desired, the payment in that 
case may be one dollar with order and the promise to pay 
the amount remaining due, one dollar per month. 

The books are delivered free upon receipt of the first 
installment payment. 

There is only one condition attached to this liberal 
offer. We require a reference as to the character and re- 
liability of the intending purchaser, but in place of this a 
statement of where employed, how long and in what 
position, will be sufficient. 

As soon as a payment is received a letter is written in 
acknowledgment, and in this letter a " safety envelope " 
will also be sent for the next installment due. 

A printed order-blank with agreement, is furnished 
upon request, but this is not necessary. A simple order 
to send the books (with reference or statement) with the 
first payment will receive prompt attention and shipment. 



The time to order these books is now, as the ver5 r pith of 
this method of payment is to avoid the waste of valuable time in 
studying them. This always has to be done in advance of 
"getting a raise" or securing a new position. 

A long experience has shown the satisfactory workings of 
this plan of payments. It has increased theamount of the sales 
and put the advantages to be derived from the use of the books 
within the easy reach of hundreds of worthy persons. It is 
easily true that one thousand men hold advanced situations 
who owe them to these useful books. If one hundred dollars 
per year is the average increased pay for each it will show an 
added income of one hundred thousand do lars annually for 
our patrons. More than twenty-five thousand of the books 
have been sold to the date of the issue of this catalogue, each 
one of which has been a lifter (or lever) for the attentive student 
of its contents. 



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NOW TO S END MONE Y BY MAIL 

Post Office Money Orders 

can be obtained at the post 

offices of most of 

the large towns. 

fcFor the small 

amount of five 

cents you can buy 

a Money Order for 

an amount under 

five dollars, payable at the 

New York post-office, and 

we will be responsible for its 

safe arrival. 

Express Money Orders 
can be obtained at any office 
of the American Express 
Company, the United States 
Express Company, the Pacific Express Company, Wells 
Fargo & Co. Kxpress Company, and Northern Pacific 
Express Company. We will be responsible for money 
sent by either of them. The price of an order, for any 
amount less than five dollars, is five cents. We recom- 
mend this as being a safe and convenient way of for- 
warding money. 

Registered Letters. If an Express or Money Order 
Post-office is not within your reach your postmaster 
will register the letter you wish to send us on payment of 
ten cents (including postage). Then, if the letter be 
lost or stolen, it can be traced. You can send money 
in this way at our risk. 

Bank Drafts. A Draft upon any country or city 
bank in the United States or Canada, we can use, if it is 
made payable to, the order of Theo. Audel & Co. 
Postage Stamps are acceptable in small amounts. 

THEO. AUDEL & CO., 63 S^&ftfc N Y. 




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fo^s&ray" 




SfeJllWi 



